Authen-SASL: Improper Handling of Highly Compressed Data (Data Amplification) (CVE-2026-21441)
Published
What is affected, what to do
A flaw was found in urllib3. When processing HTTP redirect responses during data streaming, the library automatically reads and decompresses the full response body without enforcing configured size limits.
Update Authen-SASL to version 2.2100, DBI to version 1.653, perl to version 5.42.3-RC1.
- Affected
- Urllib3
gte 1.22, < 2.6.3..*
- Urllib3
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Metrics
8.9
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v4
7.5
CVSS v3
Severity High on the scale from 0 to 10.
2.9 %
EPSS score
Moderate — model estimates 1-10% exploitation likelihood.
Source: FIRST EPSS, percentile 86.9
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 87.59 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 8.9 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 7.5
CVSS v4
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 8.9
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 2.9 %
- Moderate — model estimates 1-10% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 86.9
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-409
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
A flaw was found in urllib3. When processing HTTP redirect responses during data streaming, the library automatically reads and decompresses the full response body without enforcing configured size limits. A malicious server can exploit this by serving an excessively compressed response, bypassing decompression bomb safeguards. This issue leads to high memory and processor consumption, resulting in a Denial of Service (DoS) on the client.
Source: BSI WID Portal
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| — | Authen-SASL |
|
|
| — | Date-Manip |
|
|
| — | DBI |
|
|
| — | perl |
|
|
| acl project | acl |
|
|
| Apache Software Foundation | Apache Commons BeanUtils 1.x |
|
|
| Apache Software Foundation | Apache Commons BeanUtils 2.x |
|
|
| Apache Software Foundation | Apache Commons Lang |
|
|
| Apache Software Foundation | Apache FreeMarker |
|
|
| Apache Software Foundation | Apache HTTP Server |
|
|
| Apache Software Foundation | Apache HttpComponents Core |
|
|
| Apache Software Foundation | Apache Log4j API |
|
|
| Apache Software Foundation | Apache Log4j JSON Template Layout |
|
|
| Apache Software Foundation | Apache Portable Runtime Utility |
|
|
| Apache Software Foundation | Apache Shiro |
|
|
| Apache Software Foundation | Apache Thrift |
|
|
| Apache Software Foundation | Apache Tomcat |
|
|
| curl | curl |
|
|
Distribution and container packages (6)
Downstream packages (e.g. Bitnami, Debian, Ubuntu, Red Hat). Versions refer to the distribution, not the vendor.
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| bitnami | apr-util |
|
|
| bitnami | fluent-bit |
|
|
| bitnami | node-min |
|
|
| bitnami | thrift |
|
|
From bundled advisories, not CVE-specific (133)
Product list of a bundled advisory that does not state which product this CVE affects.
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apache | HTTP Server |
|
|
| Apache | log4j |
|
|
| Apache | Tomcat |
|
|
| Apache | Tomcat Native |
|
|
| Atlassian | Bamboo |
|
|
| Atlassian | Bamboo Data Center |
|
|
| Atlassian | Bamboo Data Center LTS |
|
|
| Atlassian | Bamboo LTS |
|
|
| Atlassian | Bitbucket |
|
|
| Atlassian | Bitbucket Data Center |
|
|
| Atlassian | Bitbucket Data Center LTS |
|
|
| Atlassian | Bitbucket LTS |
|
|
| Atlassian | Confluence |
|
|
Affected operating systems
| Family | Vendor | Product | Version |
|---|---|---|---|
| Linux | ubuntu | bind9 | bionic |
| Linux | ubuntu | bind9 | focal |
| Linux | ubuntu | bind9 | jammy |
| Linux | ubuntu | bind9 | noble |
| Linux | ubuntu | bind9 | resolute |
| Linux | ubuntu | bind9 | trusty |
| Linux | ubuntu | bind9 | xenial |
| Linux | redhat | enterprise_linux | 10.0 |
| Linux | redhat | enterprise_linux | 8.0 |
| Linux | redhat | enterprise_linux | 7.0 |
| Linux | redhat | enterprise_linux | 6.0 |
| Linux | redhat | enterprise_linux | 9.0 |
| Linux | ubuntu | libauthen-sasl-perl | bionic |
| Linux | ubuntu | libauthen-sasl-perl | focal |
| Linux | ubuntu | libauthen-sasl-perl | jammy |
| Linux | ubuntu | libauthen-sasl-perl | noble |
| Linux | ubuntu | libauthen-sasl-perl | resolute |
| Linux | ubuntu | libauthen-sasl-perl | trusty |
| Linux | ubuntu | libauthen-sasl-perl | xenial |
| Linux | ubuntu | libdbi-perl | bionic |
| Linux | ubuntu | libdbi-perl | focal |
| Linux | ubuntu | libdbi-perl | jammy |
| Linux | ubuntu | libdbi-perl | noble |
| Linux | ubuntu | libdbi-perl | resolute |
Weakness classes (CWE)
CWE-409Improper Handling of Highly Compressed Data (Data Amplification)
Base
The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.
Entry at MITRE CWE-409
References & sources
- github.comfluent/fluent-bit/security/advisories/GHSA-jrp8-r9hx-gf73x_refsource_CONFIRM
- github.comfluent/fluent-bit/pull/11945x_refsource_MISC
- github.comfluent/fluent-bit/commit/45486556be9d023e194665e243f156b228e195…x_refsource_MISC
- github.comfluent/fluent-bit/releases/tag/v5.0.8x_refsource_MISC
- NVD (NIST)vuln/detail/CVE-2026-61674web
- oracle.comOracle AdvisoryVendor advisory
- spring.iosecurity/cve-2026-41855
- NVD (NIST)vuln/detail/CVE-2026-41855advisory
- github.comspring-projects/spring-framework/commit/9bec52b1ec741976658e916…web
- github.comspring-projects/spring-frameworkpackage
- sourceware.orgbugzilla/show_bug.cgi?id=33998euvd
- Siemens ProductCERTproductcert/html/ssa-082556.html
- openssl-library.orgOpenSSL AdvisoryVendor advisory
- github.com4.0.2 git commitPatch
- github.com3.6.4 git commitPatch
- github.com3.5.8 git commitPatch
- github.com3.4.7 git commitPatch
- github.com3.0.22 git commitPatch
- github.comopen-telemetry/opentelemetry-java/security/advisories/GHSA-rcgg…web, x_refsource_CONFIRM
- NVD (NIST)vuln/detail/CVE-2026-45292advisory
Reanalysis & status changes
Chronological NVD audit events for this CVE — reanalyses, CVSS updates, CPE diffs.
CVE Modified0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- Affected: after Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/21xxx/CVE-2026-21441.json">CVE-2026-21441</a>
CVE Modified0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- Affected: after Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/21xxx/CVE-2026-21441.json">CVE-2026-21441</a>
CVE Modified0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- Affected: after Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/21xxx/CVE-2026-21441.json">CVE-2026-21441</a>
CVE Modified0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- Affected: after Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/21xxx/CVE-2026-21441.json">CVE-2026-21441</a>
CVE Modified0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- Affected: after Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/21xxx/CVE-2026-21441.json">CVE-2026-21441</a>
- Reference: after https://access.redhat.com/errata/RHSA-2026:61628
Linked CVEs
| Severity | CVE | Title | CVSS | Exploitation |
|---|---|---|---|---|
| Medium | CVE-2026-91629 | Oracle Communications Billing and Revenue Management: security vulnerability | 4.7 | — |
| Medium | CVE-2026-91628 | Oracle Communications Billing and Revenue Management: security vulnerability | 5.5 | — |
| High | CVE-2026-91627 | Oracle Communications Billing and Revenue Management: security vulnerability | 7.8 | — |
| Low | CVE-2026-91614 | Oracle Communications Unified Inventory Management: security vulnerability | 3.3 | — |
| Low | CVE-2026-91613 | Oracle Communications Unified Inventory Management: security vulnerability | 3.3 | — |
| Low | CVE-2026-91612 | Oracle Communications Unified Inventory Management: security vulnerability | 3.3 | — |
| Critical | CVE-2026-8763 | Name Constraints bypass via trailing dot in rfc822Name and URI | 9.1 | — |
| Medium | CVE-2026-87297 | Oracle Communications Billing and Revenue Management: security vulnerability | 6.7 | — |
| High | CVE-2026-8643 | pip can extract console_scripts and gui_scripts outside installation directory | 8.0 | — |
| Critical | CVE-2026-86219 | Authen-SASL: Authentication Bypass by Capture-replay | 9.8 | — |
| Critical | CVE-2026-84939 | Apache FreeMarker: Relative Path Traversal | 9.1 | — |
| Medium | CVE-2026-83406 | Oracle Communications Billing and Revenue Management: security vulnerability | 6.7 | — |
| Critical | CVE-2026-78030 | DBI: Unsafe Reflection | 9.8 | — |
| High | CVE-2026-75596 | Netty: Inefficient Algorithmic Complexity | 7.5 | — |
| Critical | CVE-2026-75595 | Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext | 9.1 | — |
| Medium | CVE-2026-7168 | cross-proxy Digest auth state leak | 5.3 | — |
| High | CVE-2026-69247 | Pyca Cryptography: Observable Timing Discrepancy | — | — |
| Critical | CVE-2026-68525 | Apache Tomcat: Redirect after FORM auth may bypass method specific constraints | 9.1 | — |
| High | CVE-2026-68497 | jackson-databind: Duration XMLGregorianCalendar Unbounded Number Parse DoS | 7.5 | — |
| High | CVE-2026-68494 | FasterXML Jackson-core: Allocation of Resources Without Limits or Throttling | — | — |
| Critical | CVE-2026-6653 | libxml2: Use after free in xmlParseInternalSubset via improper entity resolution handling | 9.8 | — |
| Critical | CVE-2026-64193 | Net::DNS versions through 1.55 for Perl allow remote execution injection via EDNS EXTENDED ERROR | 9.8 | — |
| High | CVE-2026-63639 | Valkey: UAF in stream deserialization may lead to remote code execution | 8.8 | — |
| High | CVE-2026-63388 | Libevent: Reachable Assertion | 8.4 | — |
Show 64 more CVEs
| Severity | CVE | Title | CVSS | Exploitation |
|---|---|---|---|---|
| Critical | CVE-2026-61674 | Fluent Bit: Remote stack buffer overflow in Fluent Bit `out_forward` Secure-Forward `PONG` handler | — | — |
| High | CVE-2026-60075 | Date-Manip: Inefficient Regular Expression Complexity | 7.5 | — |
| Medium | CVE-2026-59949 | Yawkat Lz4-java: NULL Pointer Dereference | 6.5 | — |
| High | CVE-2026-59901 | Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang | 7.5 | — |
| Medium | CVE-2026-59889 | jackson-databind: @JsonView ypassed for @JsonUnwrapped container properties on deserialization | 6.5 | — |
| High | CVE-2026-5928 | Potential buffer under-read in ungetwc | 7.5 | — |
| High | CVE-2026-58389 | Apache Thrift: Rust binary protocol non-strict path missing string size limit | 7.5 | — |
| Critical | CVE-2026-58016 | Glib: integer underflow in gio/gdbusintrospection.c via "g_dbus_node_info_new_for_xml" | 9.1 | — |
| High | CVE-2026-58014 | Glib: off-by-one error in glib/gkeyfile.c via "g_key_file_get_locale_string_list" | 8.6 | — |
| High | CVE-2026-5795 | Eclipse Jetty: Sensitive Information in Resource Not Removed Before Reuse | 7.4 | — |
| Medium | CVE-2026-5704 | Tar: tar: hidden file injection via crafted archives | 5.5 | — |
| High | CVE-2026-56740 | JLine: Unauthenticated Remote Memory Exhaustion via Unbounded Telnet NEW-ENVIRON Variables | 7.5 | — |
| Low | CVE-2026-56130 | Apache Shiro: Remember-me cookie isn't checked for expiry on the server | — | — |
| Critical | CVE-2026-55971 | Apache Thrift: C++ ZLIB heap buffer overflow (write) in THeaderTransport::untransform() | 9.8 | — |
| Medium | CVE-2026-55956 | Apache Tomcat: Security constraints for default servlet ignored method | 6.5 | — |
| Medium | CVE-2026-55858 | org.mariadb.jdbc:mariadb-java-client has Inappropriate Encoding for Output Context | 5.9 | — |
| High | CVE-2026-55831 | Netty SPDY SETTINGS frame count materializes unbounded settings map | 7.5 | — |
| Critical | CVE-2026-54906 | Ruby-concurrency Concurrent-ruby: Missing Lock Check | 9.8 | — |
| High | CVE-2026-54874 | Excessive Memory Use Buffering DTLS Records for a Future Epoch | 7.5 | — |
| High | CVE-2026-54512 | FasterXML Jackson-databind: Incomplete List of Disallowed Inputs | 8.1 | — |
| Critical | CVE-2026-5450 | scanf %mc off-by-one heap buffer overflow | 9.8 | — |
| High | CVE-2026-54399 | Apache HttpComponents Core: Unbounded HTTP Header/Line Length in Default Configuration | 7.5 | — |
| High | CVE-2026-54369 | acl < 2.4.0 Symlink Traversal Privilege Escalation via libacl Functions | 7.1 | — |
| High | CVE-2026-54291 | Silent channel-binding authentication downgrade via unsupported certificate algorithms | 5.9 | — |
| Medium | CVE-2026-49844 | Apache Log4j API: Improper serialization of non-finite floating-point values in MapMessage.asJson() | 5.9 | — |
| Critical | CVE-2026-4800 | lodash vulnerable to Code Injection via `_.template` imports key names | 9.8 | — |
| Medium | CVE-2026-45292 | opentelemetry-java: Unbounded Memory Allocation in W3C Baggage Propagation | 5.3 | — |
| Medium | CVE-2026-41989 | GnuPG Libgcrypt: Out-of-bounds Write | 6.7 | — |
| Critical | CVE-2026-41855 | Spring Framework Unsafe Deserialization via Jackson JMS Converters | 9.8 | — |
| Medium | CVE-2026-41001 | Predictable Temp Directory in Artemis Auto-configuration | 5.3 | — |
| Critical | CVE-2026-39892 | cryptography has a buffer overflow if non-contiguous buffers were passed to APIs | 9.8 | — |
| High | CVE-2026-34487 | Apache Tomcat: Cloud membership for clustering component exposed the Kubernetes bearer token | 7.5 | — |
| High | CVE-2026-34481 | Apache Log4j JSON Template Layout: Improper Encoding or Escaping of Output | 7.5 | — |
| Medium | CVE-2026-32327 | Apache Portable Runtime Utility: apr-util XML stack recursion crash | 5.3 | — |
| High | CVE-2026-29167 | Apache HTTP Server: mod_ldap per-dir use-after-free | 8.6 | — |
| Critical | CVE-2026-28369 | Undertow: undertow: request smuggling via malformed http request headers | 9.1 | — |
| High | CVE-2026-27601 | Underscore.js has unlimited recursion in _.flatten and _.isEqual, potential for DoS attack | 7.5 | — |
| Medium | CVE-2026-22702 | virtualenv Has TOCTOU Vulnerabilities in Directory Creation | 4.5 | — |
| Low | CVE-2026-21716 | Node: security vulnerability | 3.3 | — |
| High | CVE-2026-21441 | Urllib3: Improper Handling of Highly Compressed Data (Data Amplification) | 7.5 | — |
| High | CVE-2026-13321 | DNSSEC Validation Bypass via Out-of-Zone NSEC Next Field | 8.6 | — |
| Critical | CVE-2026-13221 | Perl: Integer Overflow or Wraparound | 9.1 | — |
| Medium | CVE-2026-101807 | Oracle Communications Billing and Revenue Management: security vulnerability | 4.8 | — |
| Medium | CVE-2026-101793 | Oracle Communications BRM - Elastic Charging Engine: security vulnerability | 5.5 | — |
| Medium | CVE-2026-101792 | Oracle Communications BRM - Elastic Charging Engine: security vulnerability | 5.9 | — |
| High | CVE-2026-101791 | Oracle Communications BRM - Elastic Charging Engine: security vulnerability | 8.1 | — |
| Low | CVE-2026-101790 | Oracle Communications BRM - Elastic Charging Engine: security vulnerability | 3.3 | — |
| Critical | CVE-2026-101765 | Oracle Communications Billing and Revenue Management: Missing Authentication for Critical Function | 9.1 | — |
| Medium | CVE-2026-101764 | Oracle Communications Billing and Revenue Management: security vulnerability | 5.5 | — |
| Critical | CVE-2026-101763 | Oracle Communications BRM - Elastic Charging Engine: Missing Authentication for Critical Function | 9.8 | — |
| High | CVE-2026-101759 | Oracle Communications Billing and Revenue Management: security vulnerability | 7.5 | — |
| High | CVE-2026-101758 | Oracle Communications Billing and Revenue Management: security vulnerability | 8.2 | — |
| High | CVE-2026-101680 | Oracle Communications Billing and Revenue Management: security vulnerability | 7.4 | — |
| Medium | CVE-2026-101606 | Oracle Communications Billing and Revenue Management: security vulnerability | 6.5 | — |
| High | CVE-2026-101604 | Oracle Communications Unified Inventory Management: security vulnerability | 7.5 | — |
| High | CVE-2026-101603 | Oracle Communications Unified Inventory Management: security vulnerability | 7.5 | — |
| Critical | CVE-2026-10050 | Digest authentication lossy encoding | 9.1 | — |
| Medium | CVE-2025-48924 | Apache Commons Lang: Uncontrolled Recursion | 5.3 | — |
| High | CVE-2025-48734 | Apache Commons BeanUtils 1.x: Improper Access Control | 8.8 | — |
| High | CVE-2025-13151 | GnuTLS Libtasn1: Stack-Based Buffer Overflow | 7.5 | — |
| Medium | CVE-2024-6763 | Jetty URI parsing of invalid authority | 5.3 | — |
| High | CVE-2024-47072 | Xstream: Stack-based Buffer Overflow | 7.5 | — |
| Medium | CVE-2024-38356 | TinyMCE Cross-Site Scripting (XSS) vulnerability using noneditable_regexp option | 6.1 | — |
| Critical | CVE-2021-42576 | Microco Bluemonday: security vulnerability | 9.8 | — |
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<a href="https://intel.neosec.eu/en/cve/CVE-2026-21441"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-21441.svg?lang=en" alt="CVE-2026-21441 – NEOSEC Intel" height="20"></a>