CVE-2025-66037: OpenSC is an open source smart card tools and middleware

Q: How do I fix CVE-2025-66037?

opensc: upgrade to 0.27.0. Exact commands for each OS are on this page.

Q: Is CVE-2025-66037 being exploited?

CVE-2025-66037 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-66037 affect?

CVE-2025-66037 affects opensc. Severity is low (CVSS 3.9). 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,

Q: How urgent is CVE-2025-66037?

Priority 23/100. Public exploit reference

Routine

LOW 3.9UPGRADE

CVE-2025-66037 is a low-severity flaw (CVSS 3.9) affecting opensc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	3.9 (Low)
Attack vector	Physical
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-125
Published	2026-03-30
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: opensc project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-30 18:16 UTCPublished CVE record published
2026-06-17 09:56 UTCUpdated Record last modified

opensc project opensc UPGRADE

Affected: < 0.27.0

Fixed in: 0.27.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy opensc || rpm -q opensc || opensc --version

2. UPGRADE to 0.27.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade opensc

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade opensc

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-66037?

opensc: upgrade to 0.27.0. Exact commands for each OS are on this page.

Is CVE-2025-66037 being exploited?

CVE-2025-66037 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-66037 affect?

CVE-2025-66037 affects opensc. Severity is low (CVSS 3.9). 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,

How urgent is CVE-2025-66037?

Priority 23/100. Public exploit reference

Related CVEs

CVE-2026-40510 LOW 3.8 UPGRADE OpenSC before 0.27.0-rc1, fixed in commit 3f24f0b, contains a stack buffer overflow vulnerability in piv_proce
CVE-2026-40528 LOW 3.8 UPGRADE OpenSC before 0.27.0, fixed in commit 0358817, contains a stack and heap buffer overrun vulnerability in the d
CVE-2025-66215 LOW 3.8 UPGRADE OpenSC is an open source smart card tools and middleware
CVE-2025-66038 LOW 3.9 UPGRADE OpenSC is an open source smart card tools and middleware
CVE-2025-49010 LOW 3.8 UPGRADE OpenSC is an open source smart card tools and middleware

References

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