CVE-2026-34181: OpenSSL

High severity, CVSS 7.4. EPSS: 0.2% chance of exploitation in the next 30 days.

Issue Summary: The PKCS#12 file processing fails to perform sufficient input validation for files that use Password-Based Message Authentication Code 1 (PBMAC1) integrity mechanism allowing a certificate and private key forgery. Impact Summary: An attacker impersonating a user can cause a service reading PKCS#12 files to accept forged certificates and private keys with a 1 in 256 probability. If a service accepting PKCS#12 files is using passwords for authenticating the received files, the attacker can create unencrypted PKCS#12 files that use PBMAC1 authentication that specifies an HMAC key of only one byte, allowing them to craft a file that will be accepted with a 1 in 256 probability. That would then cause the service to accept a certificate and private key controlled by the attacker. The FIPS modules are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

Affected products

• OpenSSL OpenSSL: from 3.4.0, before 3.4.6 (fixed in 3.4.6); from 3.5.0, before 3.5.7 (fixed in 3.5.7); from 3.6.0, before 3.6.3 (fixed in 3.6.3); version 4.0.0 only

Published 2026-06-09. Last modified 2026-07-23.