CVE-2026-42766

Public on 2026-06-09
Modified on 2026-06-11
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.
Severity
Medium severity
Medium
See what this means
CVSS v3 Base Score
5.9
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 2 - Core edk2 2026-06-22 ALAS2-2026-3363 Fixed
Amazon Linux 2 - Core openssl 2026-06-22 ALAS2-2026-3365 Fixed
Amazon Linux 2023 openssl 2026-06-22 ALAS2023-2026-1853 Fixed
Amazon Linux 2 - Openssl-snapsafe Extra openssl-snapsafe 2026-06-22 ALAS2OPENSSL-SNAPSAFE-2026-011 Fixed
Amazon Linux 2 - Core openssl11 2026-06-22 ALAS2-2026-3364 Fixed

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H