Vulnerability · Published Jun 9, 2026 · Assigned by openssl
CVE-2026-34181PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys
High 7.4
In plain English
A high-severity security flaw in OpenSSL from OpenSSL. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | openssl | 1:3.5.5-4.el10_2.alma.1 | ALSA-2026:25237 |
| AlmaLinux:9 | openssl | 1:3.5.5-4.el9_8 | ALSA-2026:25239 |
| AlmaLinux:10 | openssl-devel | 1:3.5.5-4.el10_2.alma.1 | ALSA-2026:25237 |
| AlmaLinux:9 | openssl-devel | 1:3.5.5-4.el9_8 | ALSA-2026:25239 |
| AlmaLinux:10 | openssl-libs | 1:3.5.5-4.el10_2.alma.1 | ALSA-2026:25237 |
| AlmaLinux:9 | openssl-libs | 1:3.5.5-4.el9_8 | ALSA-2026:25239 |
| AlmaLinux:10 | openssl-perl | 1:3.5.5-4.el10_2.alma.1 | ALSA-2026:25237 |
| AlmaLinux:9 | openssl-perl | 1:3.5.5-4.el9_8 | ALSA-2026:25239 |
| Alpine:v3.22 | openssl | 3.5.7-r0 | ALPINE-CVE-2026-34181 |
| Alpine:v3.23 | openssl | 3.5.7-r0 | ALPINE-CVE-2026-34181 |
| Alpine:v3.24 | openssl | 3.5.7-r0 | ALPINE-CVE-2026-34181 |
| Debian:13 | openssl | 3.5.6-1~deb13u2 | DEBIAN-CVE-2026-34181 |
| Debian:14 | openssl | 3.6.3-1 | DEBIAN-CVE-2026-34181 |
| Rocky Linux:10 | openssl | 1:3.5.5-4.el10_2 | RLSA-2026:25237 |
| Rocky Linux:9 | openssl | 1:3.5.5-4.el9_8 | RLSA-2026:25239 |
| Ubuntu:25.10 | edk2 | no fix listed | UBUNTU-CVE-2026-34181 |
| Ubuntu:26.04:LTS | edk2 | no fix listed | UBUNTU-CVE-2026-34181 |
| Ubuntu:26.10 | edk2 | no fix listed | UBUNTU-CVE-2026-34181 |
| Ubuntu:26.04:LTS | edk2-hwe | no fix listed | UBUNTU-CVE-2026-34181 |
| Ubuntu:26.10 | edk2-hwe | no fix listed | UBUNTU-CVE-2026-34181 |
| Ubuntu:25.10 | openssl | 3.5.3-1ubuntu3.4 | UBUNTU-CVE-2026-34181 |
| Ubuntu:26.04:LTS | openssl | 3.5.5-1ubuntu3.2 | UBUNTU-CVE-2026-34181 |
Affected products (as reported)
Weakness: CWE-354 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
References
- OpenSSL Advisory vendor-advisory
- 4.0.1 git commit patch
- 3.6.3 git commit patch
- 3.5.7 git commit patch
- 3.4.6 git commit patch