CVE-2026-42766

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.

How to fix CVE-2026-42766

To remediate CVE-2026-42766, upgrade the affected package to a fixed version below.

• —upgrade to 3.5.7-r0 or later
• —no fix listed

Is CVE-2026-42766 being exploited?

No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-42766.

Affected packages (2)

• from 0, < 3.5.7-r0
• from 0

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2026-42766
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-42766