CVE-2026-44518: open-quantum-safe liboqs out-of-bounds read in XMSS verification

CVE-2026-44518 · Severity: medium · CVSS 5.3 · Published 2026-05-29

liboqs is a cryptographic library used to implement post-quantum security algorithms. A flaw in how it verifies digital signatures could allow an attacker to provide a specially crafted, shorter-than-expected signature that causes the software to read beyond its assigned memory. In practice, this would likely result in a service crash (denial of service), though it does not appear to leak sensitive data or allow unauthorized access.

Technologies: Open Quantum Safe Liboqs. Vendors: Open Quantum Safe.

Quick answers

Is CVE-2026-44518 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-44518 being exploited in the wild.
How severe is CVE-2026-44518?
Medium severity, with a CVSS score of 5.3, published 29 May 2026.
Which products and versions are affected?
Open Quantum Safe Liboqs < 0.16.0.
Is there a fix for CVE-2026-44518?
A patch was published on 2026-04-23: Fix committed to main branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-44518 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-44518?
Check whether you run Open Quantum Safe Liboqs 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 exists in the XMSS and XMSS^MT stateful signature verification implementations within liboqs. The vulnerability occurs because the internal function `xmssmt_core_sign_open` discards the caller-supplied signature length and instead uses a fixed length defined by the algorithm's parameter set to index the signature buffer. If a caller provides a buffer shorter than the expected signature size, the library reads adjacent memory during internal hash computations. While the out-of-bounds data is not returned to the caller (preventing information leakage), the read can trigger a segmentation fault if it crosses into unmapped memory pages, leading to a denial of service. The issue is fixed in version 0.16.0 by adding explicit length validation at the verification entry points.

Affected products

  • open-quantum-safe liboqs < 0.16.0

Timeline

  • 2026-04-23: patched: Fix committed to main branch
  • 2026-05-11: advisory: GitHub Security Advisory published
  • 2026-05-29: disclosed: CVE published to NVD

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.