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Vulnerability record · CVE-2021-3537 · published 14 May 2021

CVE-2021-3537: Xmlsoft libxml2 null pointer dereference vulnerability

Xmlsoft · Libxml2

A vulnerability found in libxml2 in versions before 2.9.11 shows that it did not propagate errors while parsing XML mixed content, causing a NULL dereference. If an untrusted XML document was parsed in recovery mode and post-validated, the flaw could be used to crash the application. The highest threat from this vulnerability is to system availability.

5.9 CVSS 3.1 Medium EPSS 3.5% · top 11.2% CWE-476 · NULL pointer dereference
5.9CVSS 3.1 base score, v2 4.3
3.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
19Affected product versions listed by NVD
18References
17 Jun 2026Last modified by NVD

Description

A vulnerability found in libxml2 in versions before 2.9.11 shows that it did not propagate errors while parsing XML mixed content, causing a NULL dereference. If an untrusted XML document was parsed in recovery mode and post-validated, the flaw could be used to crash the application. The highest threat from this vulnerability is to system availability.

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

Affected products

19 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.redhat.com/show_bug.cgi?id=1956522 Issue TrackingPatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2021/05/msg00008.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZOMV5J4PMZAORVT64BKLV6
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QVM4UJ3376I6ZVOYMHBNX4G
https://security.gentoo.org/glsa/202107-05 Third Party Advisory
https://security.netapp.com/advisory/ntap-20210625-0002/ Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Not Applicable
https://www.oracle.com/security-alerts/cpuoct2021.html PatchThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1956522 Issue TrackingPatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2021/05/msg00008.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZOMV5J4PMZAORVT64BKLV6
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QVM4UJ3376I6ZVOYMHBNX4G
https://security.gentoo.org/glsa/202107-05 Third Party Advisory
https://security.netapp.com/advisory/ntap-20210625-0002/ Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Not Applicable
https://www.oracle.com/security-alerts/cpuoct2021.html PatchThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-3537), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.