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

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.

Published: 2026-06-09 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-34181 is rated Low Risk (33/100): CVSS High severity, with low exploitation likelihood (EPSS 0.19%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-34181

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.00% 0.19% +0.19%
2 2026-06-10 — 0.00% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34181

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 5.2 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-34181

GitHub Security Advisory for CVE-2026-34181

GHSA-4jgc-cj59-f9mm · Severity: high — Issue Summary: The PKCS#12 file processing fails to perform sufficient input validation for files...

OS Trackers for CVE-2026-34181

vendor priority summary link
debian unimportant CVE-2026-34181 unimportant priority: Debian including 1 source packages (openssl), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-34181
redhat low — https://access.redhat.com/security/cve/CVE-2026-34181
suse medium CVE-2026-34181 severity moderate: SUSE including 51 source package names (compat-openssl098, libopenssl-1_0_0-devel, …), 299 product×package rows across 35 product lines (SUSE Liberty Linux 10, SUSE Liberty Linux 9, … (35 product lines)): Known Not Affected 285, Fixed 8, First Fixed 6. https://www.suse.com/security/cve/CVE-2026-34181/
ubuntu low CVE-2026-34181 low priority: Ubuntu including 5 source packages (edk2, nodejs, openssl, openssl-fips, openssl1.0), 35 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): not-affected 19, needs-triage 7, DNE 6, released 2, needed 1. https://ubuntu.com/security/CVE-2026-34181

Affected software / configurations for CVE-2026-34181

Vendor Product Version Raw CPE
openssl openssl >= 3.4.0, < 3.4.6 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 3.5.0, < 3.5.7 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 3.6.0, < 3.6.3 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl 4.0.0 cpe:2.3:a:openssl:openssl:4.0.0:-:*:*:*:*:*:*

References for CVE-2026-34181

cvelogic Threat Intelligence