Medium severity · published Sep 29, 2026
CVE-2026-102633
libexpat 2.7.2 through 2.8.5 Integer Overflow in expat_realloc
5.9
CVSS
0.4%
EPSS
No
On KEV
Description
libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc() function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial of service.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
libexpat · libexpat
2.7.2 through 2.8.5 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-102633
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-102633
issue-tracking
https://github.com/libexpat/libexpat/pull/1392
patch
https://github.com/libexpat/libexpat/commit/209801d7fbaf07ab74bae8cb32dd2ab9e5846118
technical-description
https://github.com/libexpat/libexpat/blob/R_2_8_5/expat/lib/xmlparse.c#L1003
product
https://github.com/libexpat/libexpat
third-party-advisory
https://www.vulncheck.com/advisories/libexpat-2.7.2-through-2.8.5-integer-overflow-in-expat-realloc
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