CVE-2026-102633: libexpat libexpat

libexpat 2.7.2 through 2.8.5 Integer Overflow in expat_realloc

CVSS 8.2 HighEPSS 0.0037 · 30th percentile

Published by the CVE Program (CNA: VulnCheck) at 29 Sept 2026, 16:04 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
libexpat	libexpat	affected 2.7.2 to 2.8.5, inclusive semver Other versions: unaffected

Identifiers

CVE-2026-102633

CNA

VulnCheck

Weakness (CWE)

CWE-190

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
8.2	High	4.0	CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	CNA (VulnCheck)Used for this record
5.9	Medium	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H	CNA (VulnCheck)

CISA KEV Not listed.
EPSS 0.0037, the 30th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 29 Sept 2026. New records show when each source confirmed them.

Sources

References from the CNA

github.com/libexpat/libexpat/pull/1392 issue-trackingpatch
github.com/libexpat/libexpat/commit/209801d7fbaf07ab74bae8cb32dd2ab9e5846118 patch
github.com/libexpat/libexpat/blob/R_2_8_5/expat/lib/xmlparse.c#L1003 technical-description
github.com/libexpat/libexpat product
www.vulncheck.com/advisories/libexpat-2.7.2-through-2.8.5-integer-overflow-in-expat-realloc third-party-advisory

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.