Is CVE-2021-45960 in the CISA KEV catalog?

No. CVE-2021-45960 is not currently on the CISA Known Exploited Vulnerabilities list.

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

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

What is the EPSS score for CVE-2021-45960?

CVE-2021-45960 has an EPSS score of 4.20% (90th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-45960?

Upgrade expat on debian 11 to 2.2.10-2+deb11u1 or later. Fixes are available for 12 affected products.

CVE & CISA-KEV Catalog

CVE-2021-45960

HIGHEPSS 90th pctl

8.8

CVSS v3

NVD

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).

CWE-682

How to fix

Remediation Available

expatDebian

Fixed in:2.2.10-2+deb11u1CVE-2021-45960

Fixed in:2.4.3-1CVE-2021-45960

expatRocky

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

expatRed Hat / RHEL

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

expat-debuginfoRed Hat / RHEL

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

expat-debuginfoRocky

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

expat-debugsourceRed Hat / RHEL

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

expat-debugsourceRocky

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

expat-develRed Hat / RHEL

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

expat-develRocky

Fixed in:0:2.2.10-1.el8_2RHSA-2025:22871

Fixed in:0:2.2.10-1.el8_4RHSA-2025:22785

expatUbuntu

Fixed in:2.1.0-4ubuntu1.4+esm4USN-5288-1

Fixed in:2.1.0-7ubuntu0.16.04.5+esm2USN-5288-1

Fixed in:2.2.5-3ubuntu0.4USN-5288-1

Fixed in:2.2.9-1ubuntu0.2USN-5288-1

lib64expat1Ubuntu

Fixed in:2.1.0-4ubuntu1.4+esm4USN-5288-1

Fixed in:2.1.0-7ubuntu0.16.04.5+esm2USN-5288-1

libexpat1Ubuntu

Fixed in:2.1.0-4ubuntu1.4+esm4USN-5288-1

Fixed in:2.1.0-7ubuntu0.16.04.5+esm2USN-5288-1

Fixed in:2.2.5-3ubuntu0.4USN-5288-1

Fixed in:2.2.9-1ubuntu0.2USN-5288-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

4.20%probability of exploitation in 30 days

90thpercentile

Elevated risk: more likely to be exploited than 90% of all known CVEs.

References

Patch3

Exploit1

openwall.com

Third-Party Advisory5

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-05-05.