CVE-2026-34181
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BaseFortify

Publication date: 2026-06-09

Last updated on: 2026-06-09

Assigner: OpenSSL Software Foundation

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.
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Meta Information
Published
2026-06-09
Last Modified
2026-06-09
Generated
2026-06-10
AI Q&A
2026-06-09
EPSS Evaluated
N/A
NVD
CVE-2026-34181
EUVD
EUVD-2026-35477
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
openssl openssl *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-354 The product does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission.
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Executive Summary

This vulnerability occurs because the PKCS#12 file processing does not perform sufficient input validation for files that use the Password-Based Message Authentication Code 1 (PBMAC1) integrity mechanism.

As a result, an attacker can create forged certificates and private keys that may be accepted by a service reading these PKCS#12 files.

Specifically, if a service uses passwords to authenticate PKCS#12 files, an attacker can craft unencrypted PKCS#12 files using PBMAC1 authentication with an HMAC key of only one byte, which allows the forged file to be accepted with a probability of 1 in 256.

Impact Analysis

This vulnerability can allow an attacker to impersonate a legitimate user by causing a service to accept forged certificates and private keys.

If the service relies on PKCS#12 files for authentication or encryption, the attacker could gain unauthorized access or perform actions under the guise of the legitimate user.

The probability of successful forgery is 1 in 256, which means there is a measurable risk of compromise.

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