Title: OpenSSL, Description: Resumen del problema: Un mensaje CMS cifrado con contraseña especialmente diseñado puede desencadenar una desreferencia de puntero NULL durante el descifrado CMS.

Resumen del impacto: Esta desreferencia de puntero NULL conduce a un fallo de la aplicación y a una denegación de servicio.

El campo CMS PasswordRecipientInfo.keyDerivationAlgorithm se define como OPCIONAL en la especificación ASN.1 y, por lo tanto, puede estar ausente en entradas especialmente diseñadas. Durante el descifrado CMS basado en contraseña, la implementación CMS de OpenSSL desreferencia este campo sin comprobar primero si estaba presente.

Un atacante que suministra un mensaje CMS de este tipo a una aplicación que realiza el descifrado CMS basado en contraseña puede desencadenar un fallo de la aplicación, lo que lleva a una denegación de servicio.

Las aplicaciones que procesan mensajes CMS cifrados con contraseña pueden verse afectadas.

Los módulos FIPS en 4.0, 3.6, 3.5, 3.4 y 3.0 no se ven afectados por este problema, ya que el código afectado está fuera del límite del módulo FIPS de OpenSSL.

{"timestamp":"2026-06-09T19:46:24.673332Z","id":"CVE-2026-42766","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}

[{"vendor":"OpenSSL","product":"OpenSSL","defaultStatus":"unaffected","versions":[{"version":"4.0.0","lessThan":"4.0.1","versionType":"semver","status":"affected"},{"version":"3.6.0","lessThan":"3.6.3","versionType":"semver","status":"affected"},{"version":"3.5.0","lessThan":"3.5.7","versionType":"semver","status":"affected"},{"version":"3.4.0","lessThan":"3.4.6","versionType":"semver","status":"affected"},{"version":"3.0.0","lessThan":"3.0.21","versionType":"semver","status":"affected"},{"version":"1.1.1","lessThan":"1.1.1zh","versionType":"custom","status":"affected"},{"version":"1.0.2","lessThan":"1.0.2zq","versionType":"custom","status":"affected"}]}]

OR
          *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 1.0.2 up to (excluding) 1.0.2zq
          *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 1.1.1 up to (excluding) 1.1.1zh
          *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.0.0 up to (excluding) 3.0.21
          *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.4.0 up to (excluding) 3.4.6
          *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.5.0 up to (excluding) 3.5.7
          *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.6.0 up to (excluding) 3.6.3
          *cpe:2.3:a:openssl:openssl:4.0.0:-:*:*:*:*:*:*

OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/056d06c1918fafbb98c1c85a02e4c47cc4e199ce Types: Patch

OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/12bc26ffb3a2be728c9b86e1cae277de5b33dfa4 Types: Patch

OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/3ff64913615d648cfbb6a6f1cf5529ae7ea829d7 Types: Patch

OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/ab52d88cb5374876d59aee3c91f9e4ccce2b7ce4 Types: Patch

OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/da26f368732b83e40e9d356fe61c3d3aaab6d2e8 Types: Patch

OpenSSL Software Foundation: https://openssl-library.org/news/secadv/20260609.txt Types: Vendor Advisory

https://github.com/openssl/openssl/commit/056d06c1918fafbb98c1c85a02e4c47cc4e199ce

https://github.com/openssl/openssl/commit/12bc26ffb3a2be728c9b86e1cae277de5b33dfa4

https://github.com/openssl/openssl/commit/3ff64913615d648cfbb6a6f1cf5529ae7ea829d7

https://github.com/openssl/openssl/commit/ab52d88cb5374876d59aee3c91f9e4ccce2b7ce4

https://github.com/openssl/openssl/commit/da26f368732b83e40e9d356fe61c3d3aaab6d2e8

https://github.com/openssl/security/commit/056d06c1918fafbb98c1c85a02e4c47cc4e199ce

https://github.com/openssl/security/commit/12bc26ffb3a2be728c9b86e1cae277de5b33dfa4

https://github.com/openssl/security/commit/3ff64913615d648cfbb6a6f1cf5529ae7ea829d7

https://github.com/openssl/security/commit/ab52d88cb5374876d59aee3c91f9e4ccce2b7ce4

https://github.com/openssl/security/commit/da26f368732b83e40e9d356fe61c3d3aaab6d2e8

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

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.

CWE-476

https://github.com/openssl/security/commit/056d06c1918fafbb98c1c85a02e4c47cc4e199ce

https://github.com/openssl/security/commit/12bc26ffb3a2be728c9b86e1cae277de5b33dfa4

https://github.com/openssl/security/commit/3ff64913615d648cfbb6a6f1cf5529ae7ea829d7

https://github.com/openssl/security/commit/ab52d88cb5374876d59aee3c91f9e4ccce2b7ce4

https://github.com/openssl/security/commit/da26f368732b83e40e9d356fe61c3d3aaab6d2e8

https://openssl-library.org/news/secadv/20260609.txt