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No exploitation reportedFix available

CVE-2021-3516

No exploitation reported by the sources we read.

  • Published2021-06-01
  • WeaknessCWE-416

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

There's a flaw in libxml2's xmllint in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by xmllint could trigger a use-after-free. The greatest impact of this flaw is to confidentiality, integrity, and availability.

Timeline

dates in UTC
  1. 2021-06-0114:15CVE publishedNVD

Versions per branch

NVD
Redhat enterprise linux
BranchAffectedFixed in
6.0= 6.0no fix published
7.0= 7.0no fix published
8.0= 8.0no fix published
Fedoraproject fedora
BranchAffectedFixed in
33.x= 33no fix published
34.x= 34no fix published
Debian debian linux
BranchAffectedFixed in
9.0= 9.0no fix published

6 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • jbcs-httpd24-apr-utilRed Hat:jboss_core_services:1::el8all versions · fixed in 0:1.6.1-91.el8jbcsand 16 other packages
  • jbcs-httpd24-apr-utilRed Hat:jboss_core_services:1::el7all versions · fixed in 0:1.6.1-91.jbcs.el7and 9 other packages
  • jbcs-httpd24-curlRed Hat:jboss_core_services:1::el7all versions · fixed in 0:7.78.0-3.jbcs.el7and 3 other packages
  • jbcs-httpd24-httpdRed Hat:jboss_core_services:1::el8all versions · fixed in 0:2.4.37-80.el8jbcsand 10 other packages
  • jbcs-httpd24-httpdRed Hat:jboss_core_services:1::el7all versions · fixed in 0:2.4.37-80.jbcs.el7and 7 other packages
  • jbcs-httpd24-libcurlRed Hat:jboss_core_services:1::el8all versions · fixed in 0:7.78.0-3.el8jbcsand 4 other packages
  • jbcs-httpd24-mod_cluster-nativeRed Hat:jboss_core_services:1::el8all versions · fixed in 0:1.3.16-10.Final_redhat_2.el8jbcsand 1 other package
  • jbcs-httpd24-mod_cluster-nativeRed Hat:jboss_core_services:1::el7all versions · fixed in 0:1.3.16-10.Final_redhat_2.jbcs.el7and 1 other package

72 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-3516 Red Hat Product Security193 products fixed · 12 known affected

    libxml2: Use-after-free in xmlEncodeEntitiesInternal() in entities.c

    compat-expat1 as a component of Red Hat Enterprise Linux 6 · compat-expat1.src as a component of Red Hat Enterprise Linux 6 · libxml2 as a component of Red Hat Enterprise Linux 6 · +9 more

  • ICSA-23-348-10 CISA5 known affected

    Siemens SIMATIC S7-1500

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) · +2 more

  • SSA-398330 Siemens ProductCERT5 known affected

    SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= V3.1.0 < V3.1.5 · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= V3.1.0 < V3.1.5 · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= V3.1.0 < V3.1.5 · +2 more

  • RHSA-2022:1389 Red Hat Product Security134 products fixed

    Red Hat Security Advisory: Red Hat JBoss Core Services Apache HTTP Server 2.4.37 SP11 security update

  • RHSA-2022:1390 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat JBoss Core Services Apache HTTP Server 2.4.37 SP11 security update

  • ICSA-21-336-06 CISA3 known affected

    Hitachi Energy APM Edge

    APM Edge: Version 3.0 · APM Edge: Version 2.0 · APM Edge: Version 1.0

2 more advisories

Full record on NVD

Fix

  1. Vendor fix CISA ICSA-23-348-10 · 5 productsUpdate to V3.1.5 or later version
  2. Vendor fix Siemens ProductCERT SSA-398330 · 1 productUpdate to V3.1.5 or later version
  3. Vendor fix Red Hat Product Security RHSA-2022:1389 · 134 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
  4. Vendor fix Red Hat Product Security RHSA-2022:1390 · 1 productBefore applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on. The References section of this erratum contains a download link for the update. You must be logged in to download the update.
  5. Vendor fix CISA ICSA-21-336-06 · 3 productsHitachi Energy recommends users update to Transformer APM Edge v4.0. This version updates the software components to remediate this vulnerability.
  6. Vendor fix Red Hat Product Security RHBA-2021:2854 · 13 productsBefore applying this update, ensure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258 For details on how to install and use MTC, refer to: https://docs.openshift.com/container-pla…

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVSS 3.17.8read 2026-10-23
  • NVDCVSS 2.06.8read 2026-10-23
  • CNAweakness (CWE)CWE-416known since 2026-10-23
  • NVDweakness (CWE)CWE-416read 2026-10-23
  • FIRST EPSSEPSS score2.0 %2026-11-08
  • OSVaffected packages—
  • GitHub Advisoriesadvisory—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2021-06-01
Last Modified
2026-10-14
NVD status
Modified
GitHub Advisory
GHSA-cfj9-6cq4-25vj

Frequently asked questions

What is CVE-2021-3516?

There's a flaw in libxml2's xmllint in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by xmllint could trigger a use-after-free. The greatest impact of this flaw is to confidentiality, integrity, and availability.

Is CVE-2021-3516 actively exploited?

Active exploitation of CVE-2021-3516 has not been confirmed. Its EPSS score was 2.0% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-3516?

CVE-2021-3516 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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