Bug 2369500 (CVE-2025-48946)

Summary: CVE-2025-48946 liboqs: liboqs affected by theoretical design flaw in HQC
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw in the HQC algorithm family in liboqs. Under specific conditions, an attacker who can capture an encrypted exchange can recover the clear text. There is currently no patch as the algorithm specification is the core issue. The HQC team is working on an updated specification. Users should follow the HQC mailing list for updates.
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Bug Depends On: 2369518, 2369517    
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Description OSIDB Bzimport 2025-05-30 20:01:43 UTC 
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.