Quick answers
- Is CVE-2026-115506 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-115506 being exploited in the wild.
- How severe is CVE-2026-115506?
- High severity, with a CVSS score of 7.5, published 22 October 2026.
- Which products and versions are affected?
- Libexpat through 2.9.0.
- Is there a fix for CVE-2026-115506?
- 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-2026-115506 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-115506?
- 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
The vulnerability exists in the accountingDiffTolerated() function in xmlparse.c, which detects entity amplification (billion laughs attacks) too late. An attacker can supply a moderately sized XML document with a large DTD and nested entity expansions to trigger excessive CPU consumption per parse. This is a timing-based denial of service affecting the XML parsing path without requiring authentication or user interaction beyond providing a malicious XML document.
Affected products
- libexpat libexpat through 2.9.0
Timeline
- 2026-10-22: disclosed