Libxml2: Use After Free (CVE-2021-3518)
Published Last modified Sources: CVE.org, OSV
What is affected, what to do
There's a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by an application linked with libxml2 could trigger a use-after-free.
Update libxml2 to version 2.9.11.
- Affected
- Libxml2
eq libxml2 2.9.11..libxml2 2.9.11
- Libxml2
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
8.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
8.8
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org, OSV
21.9 %
EPSS score
Elevated — model estimates 10-50% exploitation likelihood.
Source: FIRST EPSS, percentile 97.6
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- 120.25 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- 8.8 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- 8.8
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- 21.9 %
- Elevated — model estimates 10-50% 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- 97.6
- 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-416
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
There's a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by an application linked with libxml2 could trigger a use-after-free. The greatest impact from this flaw is to confidentiality, integrity, and availability.
Source: cvelistv5, NVD (NIST), OSV (Open Source Vulnerabilities)
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| — | libxml2 |
|
|
| netapp | active_iq_unified_manager |
|
|
| netapp | clustered_data_ontap |
|
|
| netapp | clustered_data_ontap_antivirus_connector |
|
|
| netapp | manageability_software_development_kit |
|
|
| netapp | ontap_select_deploy_administration_utility |
|
|
| netapp | snapdrive |
|
|
| oracle | communications_cloud_native_core_network_function_cloud_native_environment |
|
|
| oracle | enterprise_manager_base_platform |
|
|
| oracle | enterprise_manager_ops_center |
|
|
| oracle | mysql_workbench |
|
|
| oracle | peoplesoft_enterprise_peopletools |
|
|
| oracle | real_user_experience_insight |
|
|
| redhat | jboss_core_services |
|
|
| xmlsoft | libxml2 |
|
|
Vendors and products
- Debian Debian Linux
- Fedora Project Infrastructure Fedora
- NetApp Active IQ Unified Manager
- NetApp FreeBSD
- NetApp Clustered Data Ontap Antivirus Connector
- NetApp Hci H410c Firmware
- NetApp Manageability Software Development Kit
- NetApp NetApp ONTAP Select Deploy administration utility
- NetApp NetApp SnapDrive
- Oracle Communications Cloud Native Core Network Function Cloud Native Environment
- Oracle Oracle Enterprise Manager Base Platform
- Oracle Oracle Enterprise Manager Ops Center
Affected operating systems
| Linux | debian | debian_linux | 9.0 |
| Linux | redhat | enterprise_linux | 8.0 |
| Other | fedoraproject | fedora | 33 |
| Other | fedoraproject | fedora | 34 |
| Other | netapp | hci_h410c_firmware | — |
Weakness classes (CWE)
CWE-416Use After Free
Variant
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Entry at MITRE CWE-416
References & sources
- NVD (NIST)vuln/detail/CVE-2021-3518advisory
- oracle.comsecurity-alerts/cpuoct2021.htmlweb, x_refsource_MISC
- oracle.comsecurity-alerts/cpujul2022.htmlweb, x_refsource_MISC
- oracle.comsecurity-alerts/cpuapr2022.htmlweb, x_refsource_MISC
- support.apple.comkb/HT212605web, x_refsource_CONFIRM
- support.apple.comkb/HT212604web, x_refsource_CONFIRM
- support.apple.comkb/HT212602web, x_refsource_CONFIRM
- support.apple.comkb/HT212601web, x_refsource_CONFIRM
- security.netapp.comadvisory/ntap-20210625-0002web
- security.gentoo.orgGLSA-202107-05web, Vendor advisory, x_refsource_GENTOO
- nokogiri.orgCHANGELOG.htmlweb
- lists.fedoraproject.orgarchives/list/package-announce@lists.fedoraproject.org/message/…web
- lists.fedoraproject.orgarchives/list/package-announce@lists.fedoraproject.org/message/…web
- lists.debian.org[debian-lts-announce] 20210510 [SECURITY] [DLA 2653-1] libxml2 security updateweb, Mailing list, x_refsource_MLIST
- lists.apache.orgthread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a45089…web
- lists.apache.orgthread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b…web
- github.comsparklemotion/nokogiri/blob/2edbbef95f1dc12c1ddc5ebda71b9159026…web
- github.comsparklemotion/nokogiripackage
- github.comrubysec/ruby-advisory-db/blob/master/gems/nokogiri/CVE-2021-351…web
- bugzilla.redhat.comshow_bug.cgi?id=1954242web, x_refsource_MISC
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 modifiedRed Hat
Show 53 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —http://seclists.org/fulldisclosure/2021/Jul/54Reference added —http://seclists.org/fulldisclosure/2021/Jul/55Reference added —http://seclists.org/fulldisclosure/2021/Jul/58Reference added —http://seclists.org/fulldisclosure/2021/Jul/59Reference added —https://bugzilla.redhat.com/show_bug.cgi?id=1954242Reference added —https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3EReference added —https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3EReference added —https://lists.debian.org/debian-lts-announce/2021/05/msg00008.htmlReference added —https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZOMV5J4PMZAORVT64BKLV6YIZAFDGX6/Reference added —https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QVM4UJ3376I6ZVOYMHBNX4GY3NIV52WV/Reference added —https://security.gentoo.org/glsa/202107-05Reference added —https://security.netapp.com/advisory/ntap-20210625-0002/Reference added —https://support.apple.com/kb/HT212601Reference added —https://support.apple.com/kb/HT212602Reference added —https://support.apple.com/kb/HT212604Reference added —https://support.apple.com/kb/HT212605Reference added —https://www.oracle.com/security-alerts/cpuapr2022.htmlReference added —https://www.oracle.com/security-alerts/cpujul2022.htmlReference added —https://www.oracle.com/security-alerts/cpuoct2021.htmlReference removed http://seclists.org/fulldisclosure/2021/Jul/54—Reference removed http://seclists.org/fulldisclosure/2021/Jul/55—Reference removed http://seclists.org/fulldisclosure/2021/Jul/58—Reference removed http://seclists.org/fulldisclosure/2021/Jul/59—Reference removed https://bugzilla.redhat.com/show_bug.cgi?id=1954242—Reference removed https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E—Reference removed https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E—Reference removed https://lists.debian.org/debian-lts-announce/2021/05/msg00008.html—Reference removed https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZOMV5J4PMZAORVT64BKLV6YIZAFDGX6/—Reference removed https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QVM4UJ3376I6ZVOYMHBNX4GY3NIV52WV/—Reference removed https://security.gentoo.org/glsa/202107-05—Reference removed https://security.netapp.com/advisory/ntap-20210625-0002/—Reference removed https://support.apple.com/kb/HT212601—Reference removed https://support.apple.com/kb/HT212602—Reference removed https://support.apple.com/kb/HT212604—Reference removed https://support.apple.com/kb/HT212605—Reference removed https://www.oracle.com/security-alerts/cpuapr2022.html—Reference removed https://www.oracle.com/security-alerts/cpujul2022.html—Reference removed https://www.oracle.com/security-alerts/cpuoct2021.html—Reference type removed http://seclists.org/fulldisclosure/2021/Jul/54 Types: Mailing List, Third Party Advisory—Reference type removed http://seclists.org/fulldisclosure/2021/Jul/55 Types: Mailing List, Third Party Advisory—Reference type removed http://seclists.org/fulldisclosure/2021/Jul/58 Types: Mailing List, Third Party Advisory—Reference type removed http://seclists.org/fulldisclosure/2021/Jul/59 Types: Mailing List, Third Party Advisory—Reference type removed https://bugzilla.redhat.com/show_bug.cgi?id=1954242 Types: Issue Tracking, Patch, Third Party Advisory—Reference type removed https://lists.debian.org/debian-lts-announce/2021/05/msg00008.html Types: Mailing List, Third Party Advisory—Reference type removed https://security.gentoo.org/glsa/202107-05 Types: Third Party Advisory—Reference type removed https://security.netapp.com/advisory/ntap-20210625-0002/ Types: Third Party Advisory—Reference type removed https://support.apple.com/kb/HT212601 Types: Third Party Advisory—Reference type removed https://support.apple.com/kb/HT212602 Types: Third Party Advisory—Reference type removed https://support.apple.com/kb/HT212604 Types: Third Party Advisory—Reference type removed https://support.apple.com/kb/HT212605 Types: Third Party Advisory—Reference type removed https://www.oracle.com/security-alerts/cpuapr2022.html Types: Patch, Third Party Advisory—Reference type removed https://www.oracle.com/security-alerts/cpujul2022.html Types: Not Applicable—Reference type removed https://www.oracle.com/security-alerts/cpuoct2021.html Types: Patch, Third Party Advisory—Source identifier: secalert@redhat.com
Record modifiedCVE Program
Show 53 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —http://seclists.org/fulldisclosure/2021/Jul/54Reference added —http://seclists.org/fulldisclosure/2021/Jul/55Reference added —http://seclists.org/fulldisclosure/2021/Jul/58Reference added —http://seclists.org/fulldisclosure/2021/Jul/59Reference added —https://bugzilla.redhat.com/show_bug.cgi?id=1954242Reference added —https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3EReference added —https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3EReference added —https://lists.debian.org/debian-lts-announce/2021/05/msg00008.htmlReference added —https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZOMV5J4PMZAORVT64BKLV6YIZAFDGX6/Reference added —https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QVM4UJ3376I6ZVOYMHBNX4GY3NIV52WV/Reference added —https://security.gentoo.org/glsa/202107-05Reference added —https://security.netapp.com/advisory/ntap-20210625-0002/Reference added —https://support.apple.com/kb/HT212601Reference added —https://support.apple.com/kb/HT212602Reference added —https://support.apple.com/kb/HT212604Reference added —https://support.apple.com/kb/HT212605Reference added —https://www.oracle.com/security-alerts/cpuapr2022.htmlReference added —https://www.oracle.com/security-alerts/cpujul2022.htmlReference added —https://www.oracle.com/security-alerts/cpuoct2021.htmlReference removed http://seclists.org/fulldisclosure/2021/Jul/54—Reference removed http://seclists.org/fulldisclosure/2021/Jul/55—Reference removed http://seclists.org/fulldisclosure/2021/Jul/58—Reference removed http://seclists.org/fulldisclosure/2021/Jul/59—Reference removed https://bugzilla.redhat.com/show_bug.cgi?id=1954242—Reference removed https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E—Reference removed https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E—Reference removed https://lists.debian.org/debian-lts-announce/2021/05/msg00008.html—Reference removed https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZOMV5J4PMZAORVT64BKLV6YIZAFDGX6/—Reference removed https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QVM4UJ3376I6ZVOYMHBNX4GY3NIV52WV/—Reference removed https://security.gentoo.org/glsa/202107-05—Reference removed https://security.netapp.com/advisory/ntap-20210625-0002/—Reference removed https://support.apple.com/kb/HT212601—Reference removed https://support.apple.com/kb/HT212602—Reference removed https://support.apple.com/kb/HT212604—Reference removed https://support.apple.com/kb/HT212605—Reference removed https://www.oracle.com/security-alerts/cpuapr2022.html—Reference removed https://www.oracle.com/security-alerts/cpujul2022.html—Reference removed https://www.oracle.com/security-alerts/cpuoct2021.html—Reference type removed http://seclists.org/fulldisclosure/2021/Jul/54 Types: Mailing List, Third Party Advisory—Reference type removed http://seclists.org/fulldisclosure/2021/Jul/55 Types: Mailing List, Third Party Advisory—Reference type removed http://seclists.org/fulldisclosure/2021/Jul/58 Types: Mailing List, Third Party Advisory—Reference type removed http://seclists.org/fulldisclosure/2021/Jul/59 Types: Mailing List, Third Party Advisory—Reference type removed https://bugzilla.redhat.com/show_bug.cgi?id=1954242 Types: Issue Tracking, Patch, Third Party Advisory—Reference type removed https://lists.debian.org/debian-lts-announce/2021/05/msg00008.html Types: Mailing List, Third Party Advisory—Reference type removed https://security.gentoo.org/glsa/202107-05 Types: Third Party Advisory—Reference type removed https://security.netapp.com/advisory/ntap-20210625-0002/ Types: Third Party Advisory—Reference type removed https://support.apple.com/kb/HT212601 Types: Third Party Advisory—Reference type removed https://support.apple.com/kb/HT212602 Types: Third Party Advisory—Reference type removed https://support.apple.com/kb/HT212604 Types: Third Party Advisory—Reference type removed https://support.apple.com/kb/HT212605 Types: Third Party Advisory—Reference type removed https://www.oracle.com/security-alerts/cpuapr2022.html Types: Patch, Third Party Advisory—Reference type removed https://www.oracle.com/security-alerts/cpujul2022.html Types: Not Applicable—Reference type removed https://www.oracle.com/security-alerts/cpuoct2021.html Types: Patch, Third Party Advisory—Source identifier: af854a3a-2127-422b-91ae-364da2661108
Record modifiedSiemens ADP
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2021/3xxx/CVE-2021-3518.json">CVE-2021-3518</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-398330.htmlSource identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
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-2021-3518"><img src="https://intel.neosec.eu/badge/cve/CVE-2021-3518.svg?lang=en" alt="CVE-2021-3518 – NEOSEC Intel" height="20"></a>