7.4

CVE-2026-34181: PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys

Analyzed
AliasesALPINE-CVE-2026-34181UBUNTU-CVE-2026-34181DEBIAN-CVE-2026-34181
Published 09-06-2026Last modified 10-06-2026

Vulnerability summary

CVE-2026-34181 is a high (CVSS 7.4) vulnerability in openssl. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 31.6% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.4 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.4/10
010
High · v3.1 (CVE.org)
EPSS score
0.38%
0%100%
Low · +0.19 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 17 · Related 8
MGASA-2026-0253OPENSUSE-SU-2026:11623-1OPENSUSE-SU-2026:21744-1RHSA-2026:25237RHSA-2026:25239RHSA-2026:42825

Timeline

  1. 09-06-2026
    PublishedVulnerability first disclosed.
  2. 10-06-2026
    Last modifiedVulnerability information updated.

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 metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.38%

Chance of exploitation in the next 30 days

Percentile

32%

Versus all other CVEs

30-day change

Increase +0.19 pp

From 0.18% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard14 products
  • libcrypto3< 3.6.3-r0
  • libcrypto3-2.34< 3.6.3-r0
  • openssl< 3.6.3-r0
  • openssl-3.5< 3.5.7-r0
  • openssl-3.5-libcrypto< 3.5.7-r0
Wolfi5 products
  • libcrypto3< 3.6.3-r0
  • openssl< 3.6.3-r0
  • openssl-4.0< 4.0.1-r0
  • openssl-4.0-libcrypto< 4.0.1-r0
  • openssl-4.0-libssl< 4.0.1-r0
Ubuntu4 products
  • edk2All versions (No fix recorded)
  • edk2-hweAll versions (No fix recorded)
  • nodejsAll versions (No fix recorded)
  • openssl< 3.5.3-1ubuntu3.4 | < 3.5.5-1ubuntu3.2
Alpine1 product
  • openssl≥ 3.4.0, < 3.5.7-r0
Debian1 product
  • openssl< 3.5.6-1~deb13u2 | < 3.6.3-1
Openssl1 product
  • openssl≥ 4.0.0, < 4.0.1 | ≥ 3.4.0, < 3.4.6 | ≥ 3.5.0, < 3.5.7 | ≥ 3.6.0, < 3.6.3 | 4.0.0

6 vendors · 26 products

References

12 links
Show all 12 references