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

> Attackers can forge PKCS#12 certificates and private keys by exploiting insufficient HMAC key validation, potentially leading to impersonation or code execution.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Jun 2026
- **Updated:** 10 Jun 2026
- **Also known as:** ALPINE-CVE-2026-34181, BELL-CVE-2026-34181, DEBIAN-CVE-2026-34181, GHSA-4jgc-cj59-f9mm, JLSEC-2026-1134, MINI-647h-5wjm-hwvm, UBUNTU-CVE-2026-34181

## What is CVE-2026-34181?

CVE-2026-34181 is a high-severity vulnerability in Openssl Openssl, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

Weakness: CWE-354 (Improper Validation of Integrity Check Value)

## Which versions are affected by CVE-2026-34181?

It affects 1 product.


Products: Openssl Openssl.

## How do I fix CVE-2026-34181?

Apply the vendor's patch.

## Is CVE-2026-34181 being exploited?

There is no known exploitation of CVE-2026-34181 in the wild and no public exploit code.

## Other vulnerabilities in Openssl Openssl

- [CVE-2009-3245](https://insights.sbomify.com/CVE-2009-3245/): Null dereference in n/a (critical 10.0)
- [CVE-2006-3738](https://insights.sbomify.com/CVE-2006-3738/): Memory corruption in n/a (critical 10.0)
- [CVE-2026-63073](https://insights.sbomify.com/CVE-2026-63073/): Untrusted Sender DN Used as Format String in CMP Response Validation (critical 9.8)
- [CVE-2016-6309](https://insights.sbomify.com/CVE-2016-6309/): Use after free in n/a (critical 9.8)
- [CVE-2016-0799](https://insights.sbomify.com/CVE-2016-0799/): Integer overflow in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34181 and fix it if it is affected.

What it is: CVE-2026-34181 is a high-severity vulnerability in Openssl Openssl, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-34181 in the wild and no public exploit code.

Affected product: Openssl Openssl. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-34181/ (Markdown: https://insights.sbomify.com/CVE-2026-34181/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34181
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34181
- OSV: https://osv.dev/vulnerability/CVE-2026-34181

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34181/
Summaries are generated and may contain mistakes; the official description above is the record.