CVE-2025-15467

Issue summary: Parsing CMS AuthEnvelopedData or EnvelopedData message with

maliciously crafted AEAD parameters can trigger a stack buffer overflow.

Impact summary: A stack buffer overflow may lead to a crash, causing Denial

of Service, or potentially remote code execution.

When parsing CMS (Auth)EnvelopedData structures that use AEAD ciphers such as

AES-GCM, the IV (Initialization Vector) encoded in the ASN.1 parameters is

copied into a fixed-size stack buffer without verifying that its length fits

the destination. An attacker can supply a crafted CMS message with an

oversized IV, causing a stack-based out-of-bounds write before any

authentication or tag verification occurs.

Applications and services that parse untrusted CMS or PKCS#7 content using

AEAD ciphers (e.g., S/MIME (Auth)EnvelopedData with AES-GCM) are vulnerable.

Because the overflow occurs prior to authentication, no valid key material

is required to trigger it. While exploitability to remote code execution

depends on platform and toolchain mitigations, the stack-based write

primitive represents a severe risk.

The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this

issue, as the CMS implementation is outside the OpenSSL FIPS module

boundary.

OpenSSL 3.6, 3.5, 3.4, 3.3 and 3.0 are vulnerable to this issue.

OpenSSL 1.1.1 and 1.0.2 are not affected by this issue.