Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-06-09T00:00:00 openssl: CMS AuthEnvelopedData Processing May Accept Forged Messages 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N CWE-130

Issue Summary: Cryptographic Message Services (CMS) processing fails to perform sufficient input validation on the cipher and tag length fields of AuthEnvelopedData containers, leading to various potential compromises. Impact Summary: Attackers making use of these vulnerabilities may achieve key-equivalent functionality for a given CMS recipient and/or bypass integrity validation for a given message. In one use case, an attacker may send a CMS message containing AuthEnvelopedData with the cipher specified as a non-AEAD cipher. OpenSSL erroneously allows this selection, and attempts to decrypt and validate the message. An on-path attacker who captures one legitimate AES-GCM AuthEnvelopedData addressed to the victim can re-emit it with the recipientInfos set left byte-for-byte intact, so the victim's private key still unwraps the genuine CEK (the content-encryption key), but with the inner OID rewritten to AES-256-OFB (Output Feedback Mode, an unauthenticated keystream mode) and with an attacker-chosen IV and ciphertext. The victim initializes AES-256-OFB under the real CEK, never consults the MAC field, and CMS_decrypt() returns success. If the application under attack responds to the attacker with any indicator showing success or failure of the decryption effort, it is possible for the attacker to use this as an oracle to obtain key equivalent functionality for the CEK used for the chosen recipient of the message. In another use case, an attacker can reduce the tag length of the chosen AEAD cipher for a given AuthEnvelopedData container to be a single byte long, allowing an attacker to brute force CMS decryption, producing an integrity bypass for applications that trust CMS_decrypt() to reject modified content. The FIPS modules are not affected by this issue.

A flaw was found in OpenSSL's Cryptographic Message Services (CMS) AuthEnvelopedData processing. An on-path attacker can exploit insufficient input validation on cipher and tag length fields by sending specially crafted CMS messages. This can lead to the forging of messages or bypassing integrity validation. Consequently, an attacker may achieve key-equivalent functionality for a given CMS recipient.

Moderate: This flaw in OpenSSL's Cryptographic Message Services (CMS) AuthEnvelopedData processing could allow an on-path attacker to forge messages or bypass integrity validation. This is due to insufficient input validation on cipher and tag length fields, potentially leading to key-equivalent functionality or integrity bypass in applications utilizing affected OpenSSL versions for CMS AuthEnvelopedData. Systems configured to operate in FIPS mode are not affected by this vulnerability. To mitigate this issue, ensure that OpenSSL is operating in FIPS mode by enabling the system-wide FIPS policy. This may have broader implications for cryptographic operations on the system and should be evaluated for compatibility with existing applications. A system reboot may be required for the changes to take effect. Red Hat Enterprise Linux 10 2026-06-11T00:00:00Z RHSA-2026:25237 openssl-1:3.5.5-4.el10_2 Red Hat Enterprise Linux 9 2026-06-11T00:00:00Z RHSA-2026:25239 openssl-1:3.5.5-4.el9_8 Red Hat Enterprise Linux 9 2026-06-11T00:00:00Z RHSA-2026:25239 openssl-1:3.5.5-4.el9_8 Cost Management 4 2026-07-15T00:00:00Z RHSA-2026:39981 costmanagement/costmanagement-metrics-rhel9-operator:1783539156 Red Hat Discovery 2 2026-06-24T00:00:00Z RHSA-2026:29197 discovery/discovery-server-rhel9:1782159791 Red Hat Discovery 2 2026-06-24T00:00:00Z RHSA-2026:29197 discovery/discovery-ui-rhel9:1782166952 Red Hat Insights proxy 1.5 2026-07-01T00:00:00Z RHSA-2026:34102 insights-proxy/insights-proxy-container-rhel9:1782890503 Red Hat Update Infrastructure 5 2026-06-16T00:00:00Z RHSA-2026:26319 rhui5/cds-rhel9:1781525684 Red Hat Update Infrastructure 5 2026-06-16T00:00:00Z RHSA-2026:26319 rhui5/haproxy-rhel9:1781525671 Red Hat Update Infrastructure 5 2026-06-16T00:00:00Z RHSA-2026:26319 rhui5/installer-rhel9:1781525693 Red Hat Update Infrastructure 5 2026-06-16T00:00:00Z RHSA-2026:26319 rhui5/rhua-rhel9:1781525739 Red Hat Enterprise Linux 10 Not affected edk2 Red Hat Enterprise Linux 10 Not affected shim Red Hat Enterprise Linux 10 Not affected shim-unsigned-aarch64 Red Hat Enterprise Linux 10 Not affected shim-unsigned-x64 Red Hat Enterprise Linux 6 Not affected openssl Red Hat Enterprise Linux 7 Not affected ovmf Red Hat Enterprise Linux 8 Not affected compat-openssl10 Red Hat Enterprise Linux 8 Not affected edk2 Red Hat Enterprise Linux 8 Not affected mingw-openssl Red Hat Enterprise Linux 8 Not affected openssl Red Hat Enterprise Linux 8 Not affected shim Red Hat Enterprise Linux 8 Not affected shim-unsigned-x64 Red Hat Enterprise Linux 9 Not affected compat-openssl11 Red Hat Enterprise Linux 9 Not affected edk2 Red Hat Enterprise Linux 9 Not affected shim Red Hat Enterprise Linux 9 Not affected shim-unsigned-aarch64 Red Hat Enterprise Linux 9 Not affected shim-unsigned-x64 Red Hat OpenShift Container Platform 4 Affected rhcos https://www.cve.org/CVERecord?id=CVE-2026-34182 https://nvd.nist.gov/vuln/detail/CVE-2026-34182