Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-45960

CVE-2021-45960HIGH

n/a n/a — In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the storeAtts function in xmlparse.c can lead to realloc mis…

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   L   N  U  H  H  H    8.8   .0435   91.1     —

AFFECTED
  Product  Versions  Fixed
  n/a      n/a –     —

TIMELINE
  Jan 1   Reserved by mitre
  Jan 1   Published (CNA: mitre)
  Oct 14  EXPLOIT PUBLISHED — CVE-2021-45960. Public exploit reference added.

CWE-682 · CNA: mitre · CVSS v3.1 · 11 references · NVD status: Modified

Description

In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g., allocating too few bytes, or only freeing memory).

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
January 1, 2022	Reserved	Reserved by mitre
January 1, 2022	Published	Published (CNA: mitre)
October 14, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2021-45960. Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
n/a	n/a	—	n/a	—

Weaknesses

CWE-682

References (11)

http://www.openwall.com/lists/oss-security/2022/01/17/3 [Exploit, Mailing List, Third Party Advisory]
https://bugzilla.mozilla.org/show_bug.cgi?id=1217609 [Issue Tracking, Permissions Required, Third Party Advisory]
https://cert-portal.siemens.com/productcert/html/ssa-398330.html
https://cert-portal.siemens.com/productcert/html/ssa-484086.html
https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf [Patch, Third Party Advisory]
https://github.com/libexpat/libexpat/issues/531 [Exploit, Issue Tracking, Patch, Third Party Advisory]
https://github.com/libexpat/libexpat/pull/534 [Patch, Third Party Advisory]
https://security.gentoo.org/glsa/202209-24 [Third Party Advisory]
https://security.netapp.com/advisory/ntap-20220121-0004/ [Third Party Advisory]
https://www.debian.org/security/2022/dsa-5073 [Issue Tracking, Third Party Advisory]
https://www.tenable.com/security/tns-2022-05 [Third Party Advisory]

Authoritative record: CVE-2021-45960 at cve.org

Weaknesses: CWE-682

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-45960 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.