CVE-2026-42766

/// Technical description

Issue summary: A specially crafted password-encrypted CMS message

can trigger a NULL pointer dereference during CMS decryption.

Impact summary: This NULL pointer dereference leads to an application crash

and a Denial of Service.

The CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as

OPTIONAL in the ASN.1 specification and may therefore be absent in specially

crafted inputs. During the password-based CMS decryption the OpenSSL

CMS implementation dereferences this field without first checking whether it

was present.

An attacker who supplies such a CMS message to an application performing

password-based CMS decryption can trigger an application crash, leading to

a Denial of Service.

Applications that process password-encrypted CMS 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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References