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Vulnerability record · CVE-2026-34181 · published 9 June 2026

CVE-2026-34181: Openssl vulnerability

OOpenssl · Openssl

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.

7.4 CVSS 3.1 High EPSS 0.18% · top 93.0% CWE-354 · CWE-354
7.4CVSS 3.1 base score
0.18%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References
23 Jul 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/openssl/openssl/commit/0300eb9ddce7a0895bf301a4b0c03a9da2313a0f Patch
https://github.com/openssl/openssl/commit/79eb76a937e474bb7610a0a3dc57131dc8dc6610 Patch
https://github.com/openssl/openssl/commit/85dcbb3abaa4878af5c8fbbe11bce708fcf984a7 Patch
https://github.com/openssl/openssl/commit/ec36f2417c4ddd8cabce4b4a60a3d7a7365f2d81 Patch
https://openssl-library.org/news/secadv/20260609.txt Vendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2026-34181), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.