CVE-2026-45447

What it is

Issue summary: A specially crafted PKCS#7 or S/MIME signed message could trigger a use-after-free during PKCS#7 signature verification. Impact summary: A use-after-free may result in process crashes, heap corruption, or potentially remote code execution. When processing a PKCS#7 or S/MIME signed message, if the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a caller-owned BIO during PKCS7_verify(). A subsequent use of the BIO by the calling application results in a use-after-free condition. In the common case this occurs when the application later calls BIO_free() on the BIO originally passed to PKCS7_verify(). Depending on allocator behavior and application-specific BIO usage patterns, this may result in a crash or other memory corruption. In some application contexts this may potentially be exploitable for remote code execution. Applications that process PKCS#7 or S/MIME signed messages using OpenSSL PKCS#7 APIs may be affected. Applications using the CMS APIs for this processing are not 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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

4.0% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-06-09 17:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-18 13:18 UTC Last updatedMost recent change to the record

Details

Published

2026-06-09 17:17 UTC

Last modified

2026-09-18 13:18 UTC

Exploit probability

4.0% · EPSS, next 30 days

Weakness

CWE-416 · Use after free

Record status

Modified

Affected

• OpenSSL < 1.0.2zq
• OpenSSL < 1.1.1zh
• OpenSSL < 3.0.21
• OpenSSL < 3.4.6
• OpenSSL < 3.5.7
• OpenSSL < 3.6.3
• OpenSSL 4.0.0

Attack profile CVSS 3.1 · 8.8

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High