CVE-2026-117610
libexpat through 2.9.0 NULL Pointer Dereference via External Entity Subparser
CVSS Score
5.9
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-476 |
| Vendor | libexpat |
| Product | libexpat |
| Published | Oct 28, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
libexpat / libexpat
0 ≤ 2.9.0
References
github.com: https://github.com/libexpat/libexpat/pull/1444 github.com: https://github.com/libexpat/libexpat/commit/7b0d50e4b1d16fafd55876260701e04279a7489d github.com: https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L3468-L3510 github.com: https://github.com/libexpat/libexpat vulncheck.com: https://www.vulncheck.com/advisories/libexpat-through-2.9.0-null-pointer-dereference-via-external-entity-subparser
Credits
Minkyung Park Sebastian Pipping