Heap Buffer Over-Read Vulnerability in OpenSSL CMS Affected Products

CVE-2026-9076

What is CVE-2026-9076?

A vulnerability exists in OpenSSL's CMS decryption process that allows an attacker to exploit a heap buffer over-read. By supplying crafted CMS data, an attacker can trigger a heap out-of-bounds read in the key unwrapping function, which may lead to a Denial of Service if the resultant memory allocation borders on unmapped pages. This issue occurs without requiring any password knowledge as the over-read happens before authentication. Although the read is limited to a few bytes and does not result in disclosed information to the attacker, it can cause application crashes, thereby impacting service availability.

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