Out-of-Bounds Read in libexpat Affects Various Applications
CVE-2026-124317

6.3MEDIUM

Key Information:

Vendor

Libexpat

Status
Libexpat
Vendor
CVE Published:
7 November 2026

What is CVE-2026-124317?

The libexpat library, utilized in various applications, is susceptible to an out-of-bounds read vulnerability affecting the functions unknown_toUtf8() and unknown_toUtf16() in xmltok.c. This vulnerability arises when the library processes documents that include truncated multibyte sequences. Attackers could exploit this by supplying such documents, leading to memory leakage or potential crashes of the applications utilizing the library. Proper handling of application-registered unknown encodings is crucial to prevent this type of breach.

Affected Version(s)

libexpat 0 <= 2.10.0

References

https://github.com/libexpat/libexpat/pull/1492
patchissue-tracking
https://github.com/libexpat/libexpat/blob/a70841d9ffa64dd...
technical-description
https://github.com/libexpat/libexpat
product

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Oğuzhan Demirbaş
Sebastian Pipping
.