Review reviewCritical

CVE-2026-34182

OpenSSL OpenSSL, openssl

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 decry...

CVSS: 9.1
EPSS: 0.35%
CISA KEV: Not listed
Published: 2026.06.10

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.35%

Technical severityCVSS 9.1

Vulnerability overview

Affected product and versions

Product: OpenSSL OpenSSL, openssl
Affected versions: >= 4.0.0 < 4.0.1, >= 3.6.0 < 3.6.3, >= 3.5.0 < 3.5.7, >= 3.4.0 < 3.4.6, >= 3.0.0 < 3.0.21, 4.0.0
Fixed versions: 3.0.21, 3.4.6, 3.5.7, 3.6.3

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that OpenSSL OpenSSL, openssl and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE: CWE-354