CVE-2021-45960

HIGHNVD 8.88.8—

8.8

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).

CVSS v3: 8.8
EG Score: 8.8(medium)
EPSS: 54.8%
KEV: Not listed

Published

January 1, 2022

Last Modified

May 5, 2025

References (18)

cve@mitrehttp://www.openwall.com/lists/oss-security/2022/01/17/3
cve@mitrehttps://bugzilla.mozilla.org/show_bug.cgi?id=1217609
cve@mitrehttps://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf
cve@mitrehttps://github.com/libexpat/libexpat/issues/531
cve@mitrehttps://github.com/libexpat/libexpat/pull/534
cve@mitrehttps://security.gentoo.org/glsa/202209-24
cve@mitrehttps://security.netapp.com/advisory/ntap-20220121-0004/
cve@mitrehttps://www.debian.org/security/2022/dsa-5073
cve@mitrehttps://www.tenable.com/security/tns-2022-05
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2022/01/17/3
af854a3a-2127-422b-91ae-364da2661108https://bugzilla.mozilla.org/show_bug.cgi?id=1217609
af854a3a-2127-422b-91ae-364da2661108https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf
af854a3a-2127-422b-91ae-364da2661108https://github.com/libexpat/libexpat/issues/531
af854a3a-2127-422b-91ae-364da2661108https://github.com/libexpat/libexpat/pull/534
af854a3a-2127-422b-91ae-364da2661108https://security.gentoo.org/glsa/202209-24

Patch Availability(6)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	lib64expat1 (2.1.0-7ubuntu0.16.04.5+esm2) @ xenial	2026-05-26	ubuntu
redhat	expat-0:2.2.10-1.el8_2	2025-12-09	redhat
redhat	expat-0:2.2.10-1.el8_4	2025-12-04	redhat
redhat	expat	2022-10-26	redhat
redhat	expat-0:2.1.0-14.el7_9	2022-03-28	redhat
redhat	expat-0:2.2.5-4.el8_5.3	2022-03-16	redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(7)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 10× in last 7d / 10× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 05:28 UTCEG score recompute
2026-05-26 05:28 UTCVendor advisory
2026-05-26 05:28 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-45960?

CVE-2021-45960 is a high vulnerability published on January 1, 2022. 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).

When was CVE-2021-45960 disclosed?

CVE-2021-45960 was first published in the National Vulnerability Database on January 1, 2022, with the most recent update on May 5, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-45960 actively exploited?

CVE-2021-45960 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 54.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-45960?

CVE-2021-45960 has a CVSS v3 base score of 8.8 (NVD).

How do I remediate CVE-2021-45960?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-45960, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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CVE-2021-45960

Published

Last Modified

References (18)

Patch Availability(6)

Weakness Classification(2)

All Vendor Advisories

Data Freshness Timeline

Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-45960?

Same vendor

Same CWE

CVE-2021-45960

📅 Published

🔄 Last Modified

🔗 References (18)

Patch Availability(6)

Weakness Classification(2)

All Vendor Advisories

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-45960?

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References (18)

Frequently asked(5)

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