Quick answers
- Is CVE-2026-124317 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-124317 being exploited in the wild.
- How severe is CVE-2026-124317?
- Medium severity, with a CVSS score of 4.8, published 7 November 2026.
- Which products and versions are affected?
- Libexpat through 2.10.0.
- Is there a fix for CVE-2026-124317?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-124317 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-124317?
- Check whether you run Libexpat at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An out-of-bounds read vulnerability exists in the unknown_toUtf8() and unknown_toUtf16() functions in xmltok.c when processing application-registered unknown encodings. When a document ends with a truncated multibyte sequence, the conversion callback reads past the parse buffer boundary. This requires an application to have registered custom unknown encodings and to parse untrusted XML input.
Affected products
- libexpat libexpat through 2.10.0
Timeline
- 2026-11-07: disclosed