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CVE-2026-34181

PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys

Published
Last modified
published
Not listed in CISA KEV
Low (openssl)
Fix
Fixed in 4.0.1, 3.6.3, 3.5.7, 3.4.6
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • OpenSSL OpenSSL

    From 4.0.0 · fixed in 4.0.1; From 3.6.0 · fixed in 3.6.3; From 3.5.0 · fixed in 3.5.7; From 3.4.0 · fixed in 3.4.6

References 5

openssl-library.org

GitHub · openssl/openssl