CVE-2026-44518

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.

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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

0.22%

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-20 Improper Input Validation

CWE-125 Out-of-bounds Read

Affected Products

Vendor	Product	Versions
openquantumsafe	liboqs	< 0.15.0

References

Advisories & Patches

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

Frequently Asked Questions

What is CVE-2026-44518? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-44518? +

CVE-2026-44518 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.

What products are affected by CVE-2026-44518? +

CVE-2026-44518 affects products from openquantumsafe, specifically: liboqs. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-44518? +

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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