CVE-2026-40253: openCryptoki is a PKCS#11 library and provides tooling for Linux and AIX

Q: How do I fix CVE-2026-40253?

opencryptoki: upgrade to newer than 3.26.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-40253 being exploited?

CVE-2026-40253 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-2026-40253 affect?

CVE-2026-40253 affects opencryptoki. Severity is medium (CVSS 6.8). openCryptoki is a PKCS#11 library and provides tooling for Linux and AIX. In versions 3.26.0 and below, the BER/DER decoding functions in the shared common library (asn1.c) accept a raw pointer but no buffer length parameter, and trust atta

Q: How urgent is CVE-2026-40253?

Priority 35/100. Public exploit reference; On your watchlist

Routine

MEDIUM 6.8WATCHLISTUPGRADE

CVE-2026-40253 is a medium-severity flaw (CVSS 6.8) affecting opencryptoki. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

openCryptoki is a PKCS#11 library and provides tooling for Linux and AIX. In versions 3.26.0 and below, the BER/DER decoding functions in the shared common library (asn1.c) accept a raw pointer but no buffer length parameter, and trust attacker-controlled BER length fields without validating them against actual buffer boundaries. All primitive decoders are affected: ber_decode_INTEGER, ber_decode_SEQUENCE, ber_decode_OCTET_STRING, ber_decode_BIT_

Why this priority

Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.8 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 95%)
CISA exploited list	No
Weakness	CWE-125
Published	2026-04-16
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2026-04-16 23:16 UTCPublished CVE record published
2026-06-17 10:44 UTCUpdated Record last modified

opencryptoki project opencryptoki UPGRADE

Affected: <= 3.26.0

Fixed in: newer than 3.26.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 3.26.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade opencryptoki

Note

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

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:28256] Moderate: opencryptoki security update 2026-06-26

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-2026-40253?

opencryptoki: upgrade to newer than 3.26.0. Exact commands for each OS are on this page.

Is CVE-2026-40253 being exploited?

CVE-2026-40253 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-2026-40253 affect?

CVE-2026-40253 affects opencryptoki. Severity is medium (CVSS 6.8). openCryptoki is a PKCS#11 library and provides tooling for Linux and AIX. In versions 3.26.0 and below, the BER/DER decoding functions in the shared common library (asn1.c) accept a raw pointer but no buffer length parameter, and trust atta

How urgent is CVE-2026-40253?

Priority 35/100. Public exploit reference; On your watchlist

Related CVEs

CVE-2026-23893 MEDIUM 6.8 DOWNGRADE openCryptoki is a PKCS#11 library and provides tooling for Linux and AIX

References

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