CVE-2026-63072

A flaw was found in OpenSSL. A crafted CMS (Cryptographic Message Syntax) message can cause an 8-byte out-of-bounds heap write when it is decrypted with CMS_decrypt(). This issue occurs because the CMS decryption process incorrectly sizes the key-unwrap output buffer when using the AES-WRAP-PAD unwrap primitive. This can lead to memory corruption, resulting in a denial of service.

To exploit this flaw, an attacker needs to supply a crafted CMS message to be decrypted in an application by CMS_decrypt(). The out-of-bounds write is a fixed-size (8-byte), fixed-value (zero) heap overflow immediately past the memory allocation, causing memory corruption, but the impact is limited to a denial of service. For these reasons, this flaw has been rated with a moderate severity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.