CVE-2025-66037: OpenSC: Out of Bounds vulnerability

Severity: medium (CVSS 6.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-30 · updated 2026-06-17
Weakness: CWE-125

Description

OpenSC is an open source smart card tools and middleware. Prior to version 0.27.0, feeding a crafted input to the fuzz_pkcs15_reader harness causes OpenSC to perform an out-of-bounds heap read in the X.509/SPKI handling path. Specifically, sc_pkcs15_pubkey_from_spki_fields() allocates a zero-length buffer and then reads one byte past the end of that allocation. This issue has been patched in version 0.27.0.

Affected products

OpenSC: before 0.27.0 — fixed in 0.27.0

How to fix

Upgrade to a fixed version: OpenSC 0.27.0. Check the vendor advisory for mitigations.

References

https://github.com/OpenSC/OpenSC/security/advisories/GHSA-m58q-rmjm-mmfx
https://github.com/OpenSC/OpenSC/wiki/CVE-2025-66037

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