CVE-2026-47738 (CVSS 5.3)

Description

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Prior to 0.16.0, OQS_KEM_encaps_derand can dereference an uninitialized encaps_derand function pointer when called on NTRU-HPS-2048-509, NTRU-HPS-2048-677, NTRU-HPS-4096-821, NTRU-HPS-4096-1229, NTRU-HRSS-701, or NTRU-HRSS-1373. The affected NTRU constructors omit the OQS_KEM.encaps_derand member because those schemes do not support derandomized encapsulation, OQS_KEM objects are allocated without zero initialization, and the wrapper in src/kem/kem.c checks only that the OQS_KEM pointer is non-null before calling through the residual heap value. An application is affected only if it instantiates one of those six NTRU KEMs and invokes OQS_KEM_encaps_derand on it. The supported impact is a calling-process crash and denial of service. This issue is fixed in version 0.16.0.

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CVSS v3.1 Score

5.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS — Exploit Prediction

0.0030

Probability of exploitation

0.23%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-824 CWE-824

References

Other References

https://github.com/open-quantum-safe/liboqs/commit/80ceff0207658eba98bae8eb22ca3aa2a364f40b https://github.com/open-quantum-safe/liboqs/pull/2460 https://github.com/open-quantum-safe/liboqs/releases/tag/0.16.0 https://github.com/open-quantum-safe/liboqs/security/advisories/GHSA-jr5q-r9qx-v738

Frequently Asked Questions

What is CVE-2026-47738? +

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Prior to 0.16.0, OQS_KEM_encaps_derand can dereference an uninitialized encaps_derand function pointer when called on NTRU-HPS-2048-509, NTRU-HPS-2048-677, NTRU-HPS-4096-821, NTRU-HPS-4096-1229, NTRU-HRSS-701, or NTRU-HRSS-1373. The affected NTRU constructors omit the OQS_KEM.encaps_derand member because those schemes do not support derandomized encapsulation, OQS_KEM objects are allocated without zero initialization, and the wrapper in src/kem/kem.c checks only that the OQS_KEM pointer is non-null before calling through the residual heap value. An application is affected only if it instantiates one of those six NTRU KEMs and invokes OQS_KEM_encaps_derand on it. The supported impact is a calling-process crash and denial of service. This issue is fixed in version 0.16.0. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-47738? +

CVE-2026-47738 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0030, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-47738? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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