CVE-2026-34181
PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys
- State
- Published
- Severity
- 7.4 High
- Published
- Jun 9, 2026
- Updated
- Jun 10, 2026
- Reserved
- Mar 26, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.4 High | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N | CISA-ADP |
Weaknesses
- CWE-354 Improper Validation of Integrity Check Value
Affected Products
| Product | Versions |
|---|---|
OpenSSLOpenSSL |
|
References
- OpenSSL Advisoryvendor-advisory
- 4.0.1 git commitpatch
- 3.6.3 git commitpatch
- 3.5.7 git commitpatch
- 3.4.6 git commitpatch
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