Medium severity · published Oct 28, 2026
CVE-2026-117610
libexpat through 2.9.0 NULL Pointer Dereference via External Entity Subparser
New
5.9
CVSS
0.4%
EPSS
No
On KEV
Description
libexpat through 2.9.0 contains a NULL pointer dereference vulnerability in externalEntityInitProcessor2() in lib/xmlparse.c that mishandles the XML_TOK_NONE token from empty input. Attackers who control stream chunking can force an empty non-final first parse on an external entity subparser, causing a later parse to crash the application.
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 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
libexpat · libexpat
through 2.9.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-117610
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-117610
patch
https://github.com/libexpat/libexpat/pull/1444
patch
https://github.com/libexpat/libexpat/commit/7b0d50e4b1d16fafd55876260701e04279a7489d
technical-description
https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L3468-L3510
product
https://github.com/libexpat/libexpat
third-party-advisory
https://www.vulncheck.com/advisories/libexpat-through-2.9.0-null-pointer-dereference-via-external-entity-subparser
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