CVE-2026-117610

high

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.

References

https://www.vulncheck.com/advisories/libexpat-through-2.9.0-null-pointer-dereference-via-external-entity-subparser

https://github.com/libexpat/libexpat/pull/1444

https://github.com/libexpat/libexpat/commit/7b0d50e4b1d16fafd55876260701e04279a7489d

https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L3468-L3510

https://github.com/libexpat/libexpat

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-111545

Details

Source: Mitre, NVD

Published: 2026-10-28

Updated: 2026-10-28

Risk Information

CVSS v2

Base Score: 5.4

Vector: CVSS2#AV:N/AC:H/Au:N/C:N/I:N/A:C

Severity: Medium

CVSS v3

Base Score: 5.9

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

Severity: Medium

CVSS v4

Base Score: 8.2

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Severity: High