CVE-2026-117610
Medium
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.
SeverityMedium
CVSS5.9
Exploit probability—
Product
Libexpat
PublishedOct 28, 2026
First seenOct 28, 2026
Weakness typeCWE-476NULL pointer dereference
How to fix
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| libexpat_project libexpat | v ≤ 2.9.0 | — |
| microsoft azl3_expat_2.8.3-2 | No range specified | — |
| microsoft azl3_expat_2.9.0-1 | No range specified | — |
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