httpd parks a request worker indefinitely on a malformed chunk size sent after the headers (CVE-2026-69664)
Published Last modified Sources: OSV, CVE.org, Red Hat, Msrc Update Guide, Debian, Ubuntu, BSI
What is affected, what to do
Missing Release of Resource after Effective Lifetime vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by sending a request with a chunked body whose chunk-size line is not a hexadecimal number. The worker serving the connection is never released and no timeout reclaims it, so repeating the request across connections occupies every available worker and denies service to legitimate clients.
Update Erlang/OTP to version 28.5.0.6.
- Affected
- Erlang OTP
gte 18.1.4..* - Erlang OTP
gte 6.0.3..*
- Erlang OTP
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
8.7
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: Vendor (CNA), CVSS v4
8.7
CVSS v4
Severity High on the scale from 0 to 10.
Source: OSV, CVE.org, Red Hat, Msrc Update Guide, Debian, Ubuntu, BSI
1.0 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 61.2
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- 98.58 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- 8.7 Methodology
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- 8.7
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- 1.0 %
- Low — model estimates < 1% 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- 61.2
- High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
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
- CISA assessment (SSVC)
- Exploitation: proof of concept · automatable · Technical impact: partial
- Source: CISA Vulnrichment, as of 1 September 2026
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-772
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
Missing Release of Resource after Effective Lifetime vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by sending a request with a chunked body whose chunk-size line is not a hexadecimal number. The worker serving the connection is never released and no timeout reclaims it, so repeating the request across connections occupies every available worker and denies service to legitimate clients. No authentication is required and the default configuration is affected. The chunk-size line must arrive in a write separate from the headers. When the body accompanies the headers, httpd_request_handler:handle_body/3 calls http_chunk:decode/3 inside a try ... catch throw:Error, so the {error, {chunk_size, _}} thrown by http_chunk:decode_size/4 is answered with 400 Bad Request. When the chunk size arrives later, the decoder is resumed through a bare catch in httpd_request_handler:handle_info/2, which converts the throw into a return value rather than raising it; the resulting error tuple is then treated as the next decoder continuation, the socket is re-armed, and the worker waits for data that never comes. The request timeout has already been cancelled at the point the headers were accepted, and the periodic byte-rate check is only armed when minimum_bytes_per_second is configured, which it is not by default. This issue affects OTP from OTP 18.1.4 before OTP 27.3.4.17, OTP 28.5.0.6, and OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, 9.6.2.3, and 9.7.2.
Source: OSV (Open Source Vulnerabilities), NVD (NIST), redhat_csaf, cvelistv5, Microsoft Security Update Guide, Debian Security Advisories, Ubuntu Security Notices, BSI WID Portal, BSI CSAF
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Erlang | OTP |
|
|
| Open Source | Erlang/OTP |
|
|
Vendors and products
Affected operating systems
| Linux | debian | erlang | trixie |
| Linux | ubuntu | erlang | bionic |
| Linux | ubuntu | erlang | focal |
| Linux | ubuntu | erlang | jammy |
| Linux | ubuntu | erlang | noble |
| Linux | ubuntu | erlang | resolute |
| Linux | ubuntu | erlang | trusty |
| Linux | ubuntu | erlang | xenial |
Weakness classes (CWE)
CWE-772Missing Release of Resource after Effective Lifetime
Base
The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.
Entry at MITRE CWE-772
References & sources
- github.comGitHub AdvisoryVendor advisory, related
- cna.erlef.orgEEF CNA record for CVE-2026-69664related
- OSV (Open Source Vulnerabilities)OSV record EEF-CVE-2026-69664related
- erlang.orgErlang/OTP version orderingx_version-scheme
- github.comFix commit a3adf63 in erlang/otpPatch
- github.comFix commit df1a9ca in erlang/otpPatch
- github.comFix commit bd4e743 in erlang/otpPatch
- github.comIntroducing commit 77acb47 in erlang/otpweb, related
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedEEF
Description added or changed
Show 3 original changes
Individual changes of this event as published by NVD Type Action Before After Description changed Missing Release of Resource after Effective Lifetime vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by sending a request with a chunked body whose chunk-size line is not a hexadecimal number. The worker serving the connection is never released and no timeout reclaims it, so repeating the request across connections occupies every available worker and denies service to legitimate clients. No authentication is required and the default configuration is affected. The chunk-size line must arrive in a write separate from the headers. When the body accompanies the headers, httpd_request_handler:handle_body/3 calls http_chunk:decode/3 inside a try ... catch throw:Error, so the {error, {chunk_size, _}} thrown by http_chunk:decode_size/4 is answered with 400 Bad Request. When the chunk size arrives later, the decoder is resumed through a bare catch in httpd_request_handler:handle_info/2, which converts the throw into a return value rather than raising it; the resulting error tuple is then treated as the next decoder continuation, the socket is re-armed, and the worker waits for data that never comes. The request timeout has already been cancelled at the point the headers were accepted, and the periodic byte-rate check is only armed when minimum_bytes_per_second is configured, which it is not by default. This issue affects OTP from OTP 18.1.4 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.Missing Release of Resource after Effective Lifetime vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by sending a request with a chunked body whose chunk-size line is not a hexadecimal number. The worker serving the connection is never released and no timeout reclaims it, so repeating the request across connections occupies every available worker and denies service to legitimate clients. No authentication is required and the default configuration is affected. The chunk-size line must arrive in a write separate from the headers. When the body accompanies the headers, httpd_request_handler:handle_body/3 calls http_chunk:decode/3 inside a try ... catch throw:Error, so the {error, {chunk_size, _}} thrown by http_chunk:decode_size/4 is answered with 400 Bad Request. When the chunk size arrives later, the decoder is resumed through a bare catch in httpd_request_handler:handle_info/2, which converts the throw into a return value rather than raising it; the resulting error tuple is then treated as the next decoder continuation, the socket is re-armed, and the worker waits for data that never comes. The request timeout has already been cancelled at the point the headers were accepted, and the periodic byte-rate check is only armed when minimum_bytes_per_second is configured, which it is not by default. This issue affects OTP from OTP 18.1.4 before OTP 27.3.4.17, OTP 28.5.0.6, and OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, 9.6.2.3, and 9.7.2.Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/69xxx/CVE-2026-69664.json">CVE-2026-69664</a>Reference added —https://github.com/erlang/otp/commit/77acb473d8f056f6f534395f131c6e45693797f0Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Record modifiedEEF
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/69xxx/CVE-2026-69664.json">CVE-2026-69664</a>Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
ReceivedEEF
CVSS V4.0: AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness type: CWE-772
Description added or changed
New references:- https://cna.erlef.org/cves/CVE-2026-69664.html
- https://github.com/erlang/otp/commit/a3adf63078438c86527d704e23282b7721d8ca12
- https://github.com/erlang/otp/commit/bd4e74348c6be8a49f060da6fd48d43f3a960292
- https://github.com/erlang/otp/commit/df1a9ca4666e2fdfc44886bfaae76de086d803f6
and 3 more references
Show 11 original changes
Individual changes of this event as published by NVD Type Action Before After Description added —Missing Release of Resource after Effective Lifetime vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by sending a request with a chunked body whose chunk-size line is not a hexadecimal number. The worker serving the connection is never released and no timeout reclaims it, so repeating the request across connections occupies every available worker and denies service to legitimate clients. No authentication is required and the default configuration is affected. The chunk-size line must arrive in a write separate from the headers. When the body accompanies the headers, httpd_request_handler:handle_body/3 calls http_chunk:decode/3 inside a try ... catch throw:Error, so the {error, {chunk_size, _}} thrown by http_chunk:decode_size/4 is answered with 400 Bad Request. When the chunk size arrives later, the decoder is resumed through a bare catch in httpd_request_handler:handle_info/2, which converts the throw into a return value rather than raising it; the resulting error tuple is then treated as the next decoder continuation, the socket is re-armed, and the worker waits for data that never comes. The request timeout has already been cancelled at the point the headers were accepted, and the periodic byte-rate check is only armed when minimum_bytes_per_second is configured, which it is not by default. This issue affects OTP from OTP 18.1.4 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.CVSS added —AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XWeakness type (CWE) added —CWE-772Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/69xxx/CVE-2026-69664.json">CVE-2026-69664</a>Reference added —https://cna.erlef.org/cves/CVE-2026-69664.htmlReference added —https://github.com/erlang/otp/commit/a3adf63078438c86527d704e23282b7721d8ca12Reference added —https://github.com/erlang/otp/commit/bd4e74348c6be8a49f060da6fd48d43f3a960292Reference added —https://github.com/erlang/otp/commit/df1a9ca4666e2fdfc44886bfaae76de086d803f6Reference added —https://github.com/erlang/otp/security/advisories/GHSA-mr35-8h7w-w3gqReference added —https://osv.dev/vulnerability/EEF-CVE-2026-69664Reference added —https://www.erlang.org/doc/system/versions.html#order-of-versionsSource identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Embed badge
Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.
<a href="https://intel.neosec.eu/en/cve/CVE-2026-69664"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-69664.svg?lang=en" alt="CVE-2026-69664 – NEOSEC Intel" height="20"></a>