CVE-2021-3517

31

FAUCET Score

CVE-2021-3517 is a high-severity out-of-bounds read vulnerability in libxml2 versions prior to 2.9.11, affecting products like Debian, Fedora, NetApp, Oracle, Red Hat, and xmlsoft. An unauthenticated attacker can trigger this flaw by supplying a crafted file, potentially leading to application unavailability and some impact on confidentiality and integrity. With a CVSS score of 8.6, the attack requires low complexity and no user interaction. While there is no known active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered some community discussion and media coverage, indicating awareness.

Impacted Technologies

Vendor	Product	Version(s)	CPE
		< 2.9.11CPE matchmatch criteria	cpe:2.3:a:xmlsoft:libxml2::::::::
		Range not provided by sourceCPE matchmatch criteria	cpe:2.3:a:redhat:jboss_core_services:-:::::::*
		8.0CPE matchmatch criteria	cpe:2.3:o:redhat:enterprise_linux:8.0:::::::*
		33CPE matchmatch criteria	cpe:2.3:o:fedoraproject:fedora:33:::::::*
		34CPE matchmatch criteria	cpe:2.3:o:fedoraproject:fedora:34:::::::*

CVSS Data

CVSS version used by this source: 3.1

8.6HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

HIGH

Exploitability Score

3.9

Impact Score

4.7

CvssVersion

3.1

Exploit Intelligence

EPSS Score

8.28%

Probability of exploitation in next 30 days

EPSS Percentile

94.3%

Percentile rank of EPSS score among Peer Group

As of 2026-07-27

Model: v2026.06.15

This CVE's current EPSS score of 0.0828 is in the 91st percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (45)

elasticpatch availablevia llm_extracted

Fixed in: ['8.1.13', '8.2.10', '9.0.4', '9.0.2209.3']

microsoftpatch availablevia msrc

Product: 19055-16820Fixed in: 2.9.12-1

microsoftpatch availablevia msrc

Product: cm1 libxml2 2.9.12-1 on CBL Mariner 1.0Fixed in: 2.9.12-1

oraclepatch availablevia nvd_reference

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-httpd-0:2.4.37-80.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_cluster-native-0:1.3.16-10.Final_redhat_2.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_http2-0:1.15.7-22.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_jk-0:1.2.48-29.redhat_1.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_md-1:2.0.8-41.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_security-0:2.9.2-68.GA.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-nghttp2-0:1.39.2-41.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-openssl-1:1.1.1g-11.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-openssl-chil-0:1.0.0-11.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-openssl-pkcs11-0:0.4.10-26.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-apr-util-0:1.6.1-91.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-curl-0:7.78.0-3.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-httpd-0:2.4.37-80.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_cluster-native-0:1.3.16-10.Final_redhat_2.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_http2-0:1.15.7-22.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_jk-0:1.2.48-29.redhat_1.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_md-1:2.0.8-41.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_security-0:2.9.2-68.GA.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-nghttp2-0:1.39.2-41.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-openssl-1:1.1.1g-11.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-openssl-chil-0:1.0.0-11.jbcs.el7

redhatpatch availablevia redhat_api

Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-openssl-pkcs11-0:0.4.10-26.jbcs.el7

redhatpatch availablevia redhat_api

Product: Red Hat Enterprise Linux 8Fixed in: libxml2-0:2.9.7-9.el8_4.2

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-controller-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-log-reader-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-must-gather-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-operator-bundle:v1.4.6-5

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-registry-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-rsync-transfer-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-ui-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-velero-plugin-for-aws-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-velero-plugin-for-gcp-rhel8:v1.4.6-3

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-velero-plugin-for-microsoft-azure-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-velero-rhel8:v1.4.6-5

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-velero-plugin-rhel8:v1.4.6-4

redhatpatch availablevia redhat_api

Product: Text-Only JBCSFixed in: libxml2

redhatpatch availablevia redhat_api

Product: Red Hat Migration Toolkit for Containers 1.4Fixed in: rhmtc/openshift-migration-velero-restic-restore-helper-rhel8:v1.4.6-5

redhatpatch availablevia nvd_reference

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-apr-util-0:1.6.1-91.el8jbcs

redhatpatch availablevia redhat_api

Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-curl-0:7.78.0-3.el8jbcs

rubygemspatch availablevia ghsa

Product: nokogiriFixed in: 1.11.4

Vendor Advisories (4)

elasticllm-elastic-1862d04bb8fb6af4HIGH

February Third Party Package Updates in Splunk Enterprise

rubygemsGHSA-jw9f-hh49-cvp9high

Nokogiri contains libxml Out-of-bounds Write vulnerability

microsoft2021-May/CVE-2021-3517Important

There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability with some potential impact to confidentiality and integrity if an attacker is able to use memory information to further exploit the application.

redhatCVE-2021-3517Moderate

libxml2: Heap-based buffer overflow in xmlEncodeEntitiesInternal() in entities.c

References

bugzilla.redhat.com / show_bug.cgi

Issue TrackingPatchThird Party Advisory

lists.apache.org / thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E

lists.apache.org / thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E

lists.debian.org / debian-lts-announce/2021/05/msg00008.html

Mailing ListThird Party Advisory

lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/BZOMV5J4PMZAORVT64BKLV6YIZAFDGX6

lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/QVM4UJ3376I6ZVOYMHBNX4GY3NIV52WV

security.gentoo.org / glsa/202107-05

Third Party Advisory

security.netapp.com / advisory/ntap-20210625-0002

Third Party Advisory

security.netapp.com / advisory/ntap-20211022-0004

Third Party Advisory

oracle.com / security-alerts/cpuapr2022.html

PatchThird Party Advisory

oracle.com / security-alerts/cpujan2022.html

PatchThird Party Advisory

oracle.com / security-alerts/cpujul2022.html

Not Applicable

oracle.com / security-alerts/cpuoct2021.html

PatchThird Party Advisory