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CVE-2025-52473

liboqs secret-dependent branching in HQC reference implementation when compiled with Clang 17-20

5.9 MediumFix available

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Multiple secret-dependent branches have been identified in the reference implementation of the HQC key encapsulation mechanism when it is compiled with Clang for optimization levels above -O0 (-O1, -O2, etc). A proof-of-concept local attack exploits this secret-dependent information to recover the entire secret key. This vulnerability is fixed in 0.14.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.24%Up 0.2 points since Jul 11, 2025
90%50%10%1%

What each source reports

CVE List Score used 5.9

liboqs secret-dependent branching in HQC reference implementation when compiled with Clang 17-20

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Multiple secret-dependent branches have been identified in the reference implementation of the HQC key encapsulation mechanism when it is compiled with Clang for optimization levels above -O0 (-O1, -O2, etc). A proof-of-concept local attack exploits this secret-dependent information to recover the entire secret key. This vulnerability is fixed in 0.14.0.

Record
CVE-2025-52473
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-200
Updated
2026-11-02
EUVDEUVD-2025-21027 5.9

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Multiple secret-dependent branches have been identified in the reference implementation of the HQC key encapsulation mechanism when it is compiled with Clang for optimization levels above -O0 (-O1, -O2, etc). A proof-of-concept local attack exploits this secret-dependent information to recover the entire secret key. This vulnerability is fixed in 0.14.0.

Record
EUVD-2025-21027
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
NVD 5.9

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Multiple secret-dependent branches have been identified in the reference implementation of the HQC key encapsulation mechanism when it is compiled with Clang for optimization levels above -O0 (-O1, -O2, etc). A proof-of-concept local attack exploits this secret-dependent information to recover the entire secret key. This vulnerability is fixed in 0.14.0.

Record
CVE-2025-52473
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-200
Updated
2026-11-02
OSV 5.9

liboqs secret-dependent branching in HQC reference implementation when compiled with Clang 17-20

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Multiple secret-dependent branches have been identified in the reference implementation of the HQC key encapsulation mechanism when it is compiled with Clang for optimization levels above -O0 (-O1, -O2, etc). A proof-of-concept local attack exploits this secret-dependent information to recover the entire secret key. This vulnerability is fixed in 0.14.0.

Record
CVE-2025-52473
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-200
Updated
2026-11-02
OSVopenSUSE-SU-2025:15339-1 No score

liboqs-devel-0.14.0-1.1 on GA media

These are all security issues fixed in the liboqs-devel-0.14.0-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2025:15339-1
Updated
2026-11-02
OSVopenSUSE-SU-2026:21634-1 No score

Security update for liboqs

This update for liboqs fixes the following issues:

Changes in liboqs:

Updated to 0.16.0:

Deprecation notice:

  • SPHINCS+ was removed in 0.16.0.

Security issues:

  • Fixed uninitialized encaps_derand pointer dereference
  • CVE-2026-46344, CVE-2026-44518: Fixed out-of-bounds read in XMSS/XMSS^MT signature verification (bsc#1267007 bsc#1267001)
  • Fixed Integer underflow in CROSS crypto_sign_open()
  • Fixed incorrect array size when calling secure_clean
  • Implemented optimization barrier OQS_MEM_BLACK_BOX and applied to ct_select in FrodoKEM

Significant change:

FrodoKEM algorithm change:

  • Existing FrodoKEM in 0.15.0 was renamed to ephemeral FrodoKEM (KEM_efrodokem_<640|976|1344>_<aes|shake>), and the salted variant of FrodoKEM was added under the prior names (KEM_frodokem_<640|976|1344>_<aes|shake>).

    Ephemeral FrodoKEM is recommended for applications where each keypair will encapsulate only a small number of shared secrets and ciphertexts. Standard (salted) FrodoKEM is recommended for applications where each keypair is expected to encapsulate large number of ciphertexts. Please consult upstream for more details.

  • mldsa-native integration:

    mldsa-native is a secure, fast, and portable C90 implementation of the ML-DSA post-quantum signature standard. It also includes optimized builds for x86_64 and aarch64. It is now the default implementation behind SIG_ml_dsa_<44|65|87>.

  • Updated HQC implementation:

    The HQC implementations in liboqs were updated to 20250822 spec. Its upstream switched from PQClean to the official repo. KEM_hqc_<1|3|5> is now enabled by default.

  • MQOM integration and memory-optimized build flag:

    MQOM is a third-round candidate in NIST's Additional Digital Signatures for the PQC Standardization Process. Portable, x86_64-optimized, and memory-optimized implementations were integrate�into liboqs under OQS_ENABLE_SIG_MQOM.

  • OpenSSH implementation of NTRU Prime:

    A public-domain OpenSSH implementation of NTRUPrime761 replaced the PQClean implementation as the default backend for KEM_ntruprime_sntrup761.

Bug fixes:

  • Fixed incremental absorption bug in AVX512VL SHA3-512 #2442

  • Implemented fallback for when EVP_DigestSqueeze is unavailable #2433

  • Added API for detecting stateful signature support at runtime #2434

  • Fixed missing initialization and indexing bug in LMS #2416

  • Fixed erroneous MAYO_OK despite failed sample_solution() attempts in MAYO #2403

  • Limited pytest parallelism to prevent memory exhaustion in constrained environment #2397

  • Fixed cuPQC ML-KEM derand symbol names and #if/#elif chains #2396

  • Tightened Windows compiler detection #2394

  • Fixed mismatched macros in LMS #2379

  • Made fuzzers tolerant to disabled algorithms #2359

  • Removed inlined exponentiation in CROSS-RSDPG-1 #2357

  • Fixed incorrect arg register update in AVX512 Keccak #2330

  • Update to 0.15.0:

    • Significant changes:
      • Integrated SLH-DSA implementation from pq-code-package/slhdsa-c
      • SLH-DSA ACVP tests (#2237) -…
Record
openSUSE-SU-2026:21634-1
Updated
2026-11-02
OSVSUSE-SU-2026:23313-1 No score

Security update for liboqs

This update for liboqs fixes the following issues:

Changes in liboqs:

Updated to 0.16.0:

Deprecation notice:

  • SPHINCS+ was removed in 0.16.0.

Security issues:

  • Fixed uninitialized encaps_derand pointer dereference
  • CVE-2026-46344, CVE-2026-44518: Fixed out-of-bounds read in XMSS/XMSS^MT signature verification (bsc#1267007 bsc#1267001)
  • Fixed Integer underflow in CROSS crypto_sign_open()
  • Fixed incorrect array size when calling secure_clean
  • Implemented optimization barrier OQS_MEM_BLACK_BOX and applied to ct_select in FrodoKEM

Significant change:

FrodoKEM algorithm change:

  • Existing FrodoKEM in 0.15.0 was renamed to ephemeral FrodoKEM (KEM_efrodokem_<640|976|1344>_<aes|shake>), and the salted variant of FrodoKEM was added under the prior names (KEM_frodokem_<640|976|1344>_<aes|shake>).

    Ephemeral FrodoKEM is recommended for applications where each keypair will encapsulate only a small number of shared secrets and ciphertexts. Standard (salted) FrodoKEM is recommended for applications where each keypair is expected to encapsulate large number of ciphertexts. Please consult upstream for more details.

  • mldsa-native integration:

    mldsa-native is a secure, fast, and portable C90 implementation of the ML-DSA post-quantum signature standard. It also includes optimized builds for x86_64 and aarch64. It is now the default implementation behind SIG_ml_dsa_<44|65|87>.

  • Updated HQC implementation:

    The HQC implementations in liboqs were updated to 20250822 spec. Its upstream switched from PQClean to the official repo. KEM_hqc_<1|3|5> is now enabled by default.

  • MQOM integration and memory-optimized build flag:

    MQOM is a third-round candidate in NIST's Additional Digital Signatures for the PQC Standardization Process. Portable, x86_64-optimized, and memory-optimized implementations were integrate into liboqs under OQS_ENABLE_SIG_MQOM.

  • OpenSSH implementation of NTRU Prime:

    A public-domain OpenSSH implementation of NTRUPrime761 replaced the PQClean implementation as the default backend for KEM_ntruprime_sntrup761.

Bug fixes:

  • Fixed incremental absorption bug in AVX512VL SHA3-512 #2442

  • Implemented fallback for when EVP_DigestSqueeze is unavailable #2433

  • Added API for detecting stateful signature support at runtime #2434

  • Fixed missing initialization and indexing bug in LMS #2416

  • Fixed erroneous MAYO_OK despite failed sample_solution() attempts in MAYO #2403

  • Limited pytest parallelism to prevent memory exhaustion in constrained environment #2397

  • Fixed cuPQC ML-KEM derand symbol names and #if/#elif chains #2396

  • Tightened Windows compiler detection #2394

  • Fixed mismatched macros in LMS #2379

  • Made fuzzers tolerant to disabled algorithms #2359

  • Removed inlined exponentiation in CROSS-RSDPG-1 #2357

  • Fixed incorrect arg register update in AVX512 Keccak #2330

  • Update to 0.15.0:

    • Significant changes:
      • Integrated SLH-DSA implementation from pq-code-package/slhdsa-c
      • SLH-DSA ACVP tests (#2237)
      • Integrate…
Record
SUSE-SU-2026:23313-1
Updated
2026-11-02
OSVSUSE-SU-2026:3420-1 No score

Security update for liboqs, oqs-provider

This update for liboqs, oqs-provider fixes the following issues:

  • disable KEM_HQC and SIG_MQOM and KEM_NTRUPRIME on s390x for now, testsuite shows them not working.

Updated to 0.16.0:

Deprecation notice:

  • SPHINCS+ was removed in 0.16.0.

Security issues:

  • Fixed uninitialized encaps_derand pointer dereference
  • CVE-2026-46344, CVE-2026-44518: Fixed out-of-bounds read in XMSS/XMSS^MT signature verification (bsc#1267007 bsc#1267001)
  • Fixed Integer underflow in CROSS crypto_sign_open()
  • Fixed incorrect array size when calling secure_clean
  • Implemented optimization barrier OQS_MEM_BLACK_BOX and applied to ct_select in FrodoKEM

Significant change:

FrodoKEM algorithm change:

  • Existing FrodoKEM in 0.15.0 was renamed to ephemeral FrodoKEM (KEM_efrodokem_<640|976|1344>_<aes|shake>), and the salted variant of FrodoKEM was added under the prior names (KEM_frodokem_<640|976|1344>_<aes|shake>). Ephemeral FrodoKEM is recommended for applications where each keypair will encapsulate only a small number of shared secrets and ciphertexts. Standard (salted) FrodoKEM is recommended for applications where each keypair is expected to encapsulate large number of ciphertexts. Please consult upstream for more details.
  • mldsa-native integration: mldsa-native is a secure, fast, and portable C90 implementation of the ML-DSA post-quantum signature standard. It also includes optimized builds for x86_64 and aarch64. It is now the default implementation behind SIG_ml_dsa_<44|65|87>.
  • Updated HQC implementation: The HQC implementations in liboqs were updated to 20250822 spec. Its upstream switched from PQClean to the official repo. KEM_hqc_<1|3|5> is now enabled by default.
  • MQOM integration and memory-optimized build flag: MQOM is a third-round candidate in NIST's Additional Digital Signatures for the PQC Standardization Process. Portable, x86_64-optimized, and memory-optimized implementations were integrate�into liboqs under OQS_ENABLE_SIG_MQOM.
  • OpenSSH implementation of NTRU Prime: A public-domain OpenSSH implementation of NTRUPrime761 replaced the PQClean implementation as the default backend for KEM_ntruprime_sntrup761.

Bug fixes:

  • Fixed incremental absorption bug in AVX512VL SHA3-512 #2442
  • Implemented fallback for when EVP_DigestSqueeze is unavailable #2433
  • Added API for detecting stateful signature support at runtime #2434
  • Fixed missing initialization and indexing bug in LMS #2416
  • Fixed erroneous MAYO_OK despite failed sample_solution() attempts in MAYO #2403
  • Limited pytest parallelism to prevent memory exhaustion in constrained environment #2397
  • Fixed cuPQC ML-KEM derand symbol names and #if/#elif chains #2396
  • Tightened Windows compiler detection #2394
  • Fixed mismatched macros in LMS #2379
  • Made fuzzers tolerant to disabled algorithms #2359
  • Removed inlined exponentiation in CROSS-RSDPG-1 #2357
  • Fixed incorrect arg register update in AVX512 Keccak #2330

Update to 0.15.0:

  • Significant changes:

    • Integrated SLH-DSA…
Record
SUSE-SU-2026:3420-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
liboqs
SUSE:Linux Enterprise Server 16.0
before 0.16.0-160000.1.1
0.16.0-160000.1.1
oqs-provider
SUSE:Linux Enterprise Server 16.0
before 0.11.0.32-160000.1.1
0.11.0.32-160000.1.1
liboqs
SUSE:Linux Enterprise Server for SAP applications 16.0
before 0.16.0-160000.1.1
0.16.0-160000.1.1
oqs-provider
SUSE:Linux Enterprise Server for SAP applications 16.0
before 0.11.0.32-160000.1.1
0.11.0.32-160000.1.1
liboqs
SUSE:Linux Enterprise Module for Basesystem 15 SP7
before 0.16.0-150600.3.6.1
0.16.0-150600.3.6.1
oqs-provider
SUSE:Linux Enterprise Module for Basesystem 15 SP7
before 0.11.0.32-150600.3.9.1
0.11.0.32-150600.3.9.1
liboqs
SUSE:Linux Enterprise Server 15 SP6-LTSS
before 0.16.0-150600.3.6.1
0.16.0-150600.3.6.1
oqs-provider
SUSE:Linux Enterprise Server 15 SP6-LTSS
before 0.11.0.32-150600.3.9.1
0.11.0.32-150600.3.9.1
liboqs
SUSE:Linux Enterprise Server for SAP Applications 15 SP6
before 0.16.0-150600.3.6.1
0.16.0-150600.3.6.1
oqs-provider
SUSE:Linux Enterprise Server for SAP Applications 15 SP6
before 0.11.0.32-150600.3.9.1
0.11.0.32-150600.3.9.1
liboqs
openSUSE:Tumbleweed
before 0.14.0-1.1
0.14.0-1.1
liboqs
openSUSE:Leap 16.0
before 0.16.0-160000.1.1
0.16.0-160000.1.1
oqs-provider
openSUSE:Leap 16.0
before 0.11.0.32-160000.1.1
0.11.0.32-160000.1.1

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-52473 is a medium vulnerability (CVSS 5.9) in Open-quantum-safe Liboqs, published July 10, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.24%, the 14th percentile. Fixed in liboqs 0.16.0-160000.1.1.

References

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