# CVE-2026-34182: CMS AuthEnvelopedData Processing May Accept Forged Messages

> Attackers can bypass integrity checks or recover keys in OpenSSL CMS AuthEnvelopedData processing by manipulating cipher and tag length fields.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/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-2026-34182, AZL-89802, AZL-89861, AZL-89931, BELL-CVE-2026-34182, DEBIAN-CVE-2026-34182, GHSA-f9v2-4w9p-2cwc, JLSEC-2026-1135, MINI-379x-2r4p-4vc7, MINI-6378-ggcg-mxf2, ROOT-OS-ALPINE-317-CVE-2026-34182, UBUNTU-CVE-2026-34182

## What is CVE-2026-34182?

CVE-2026-34182 is a critical 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: Cryptographic Message Services (CMS) processing fails to perform
sufficient input validation on the cipher and tag length fields of
AuthEnvelopedData containers, leading to various potential compromises.

Impact Summary: Attackers making use of these vulnerabilities may achieve
key-equivalent functionality for a given CMS recipient and/or bypass integrity
validation for a given message.

In one use case, an attacker may send a CMS message containing
AuthEnvelopedData with the cipher specified as a non-AEAD cipher.  OpenSSL
erroneously allows this selection, and attempts to decrypt and validate the
message.

An on-path attacker who captures one legitimate AES-GCM AuthEnvelopedData
addressed to the victim can re-emit it with the recipientInfos set left
byte-for-byte intact, so the victim's private key still unwraps the genuine CEK
(the content-encryption key), but with the inner OID rewritten to AES-256-OFB
(Output Feedback Mode, an unauthenticated keystream mode) and with an
attacker-chosen IV and ciphertext. The victim initializes AES-256-OFB under the
real CEK, never consults the MAC field, and CMS_decrypt() returns success.

If the application under attack responds to the attacker with any indicator
showing success or failure of the decryption effort, it is possible for the
attacker to use this as an oracle to obtain key equivalent functionality for the
CEK used for the chosen recipient of the message.

In another use case, an attacker can reduce the tag length of the chosen AEAD
cipher for a given AuthEnvelopedData container to be a single byte long,
allowing an attacker to brute force CMS decryption, producing an integrity
bypass for applications that trust CMS_decrypt() to reject modified content.

The FIPS modules are not affected by this issue.

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

## Which versions are affected by CVE-2026-34182?

It affects 1 product.


Products: Openssl Openssl.

## How do I fix CVE-2026-34182?

Apply the vendor's patch.

## Is CVE-2026-34182 being exploited?

There is no known exploitation of CVE-2026-34182 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-2026-34182 and fix it if it is affected.

What it is: CVE-2026-34182 is a critical 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-2026-34182 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-2026-34182/ (Markdown: https://insights.sbomify.com/CVE-2026-34182/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34182
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34182
- OSV: https://osv.dev/vulnerability/CVE-2026-34182

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34182/
Summaries are generated and may contain mistakes; the official description above is the record.