CVE-2026-42767: NULL Pointer Dereference in CRMF EncryptedValue Decryption

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-09 · updated 2026-07-23
Weakness: CWE-476

Description

Issue summary: An attacker-controlled CMP (Certificate Management Protocol) server could trigger a NULL pointer dereference in a CMP client application. Impact summary: A NULL pointer dereference causes a crash of the application and a Denial of Service. An attacker controlling a CMP server (or acting as a man-in-the-middle) could craft a CMP response containing a CRMF (Certificate Request Message Format) CertRepMessage with an EncryptedValue structure where the symmAlg field has an algorithm OID but no parameters field. When the OpenSSL CMP client processes this response, the NULL dereference occurs, causing a crash of the CMP client. Applications that process untrusted CMP/CRMF messages may be affected. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

Affected products

OpenSSL: from 3.0.0 before 3.0.21; from 3.4.0 before 3.4.6; from 3.5.0 before 3.5.7; from 3.6.0 before 3.6.3; 4.0.0 — fixed in 3.0.21, 3.4.6, 3.5.7, 3.6.3

How to fix

Upgrade to a fixed version: OpenSSL 3.0.21, 3.4.6, 3.5.7, 3.6.3. Check the vendor advisory for mitigations.

References

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