CVE-2026-40253

6.8 MEDIUM 0.2% exploit odds Fix listed Memory safety Library

What it is

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_STRING, and ber_decode_CHOICE. Additionally, ber_decode_INTEGER can produce integer underflows when the encoded length is zero. An attacker supplying a malformed BER-encoded cryptographic object through PKCS#11 operations such as C_CreateObject or C_UnwrapKey, token loading from disk, or remote backend communication can trigger out-of-bounds reads. This affects all token backends (Soft, ICA, CCA, TPM, EP11, ICSF) since the vulnerable code is in the shared common library. A patch is available thorugh commit ed378f463ef73364c89feb0fc923f4dc867332a3.

At a glance

Exploitability: Can be exploited locally on the machine without logging in. High risk of service disruption.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-04-16 23:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 10:44 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 6.8 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-04-16 23:16 UTC
Last modified: 2026-06-17 10:44 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-125 · Out-of-bounds read
Record status: Analyzed

Affected

Opencryptoki Project Opencryptoki ≤ 3.26.0

Attack profile CVSS 3.1 · 6.8

Attack vector: Local
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: High

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-40253.md and follow it. Check whether this project is affected by CVE-2026-40253. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record