CVE-2026-28389

Possible NULL Dereference When Processing CMS KeyAgreeRecipientInfo

State: Published
Severity: 7.5 High
Published: Apr 7, 2026
Updated: Oct 15, 2026
Reserved: Feb 27, 2026

Description

Issue summary: During processing of a crafted CMS EnvelopedData message with KeyAgreeRecipientInfo a NULL pointer dereference can happen.

Impact summary: Applications that process attacker-controlled CMS data may crash before authentication or cryptographic operations occur resulting in Denial of Service.

When a CMS EnvelopedData message that uses KeyAgreeRecipientInfo is processed, the optional parameters field of KeyEncryptionAlgorithmIdentifier is examined without checking for its presence. This results in a NULL pointer dereference if the field is missing.

Applications and services that call CMS_decrypt() on untrusted input (e.g., S/MIME processing or CMS-based protocols) are vulnerable.

The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CISA-ADP

Weaknesses

CWE-476 NULL Pointer Dereference

Affected Products

Product	Versions
OpenSSLOpenSSL	3.6.0 to before 3.6.2Affected 3.5.0 to before 3.5.6Affected 3.4.0 to before 3.4.5Affected 3.3.0 to before 3.3.7Affected 3.0.0 to before 3.0.20Affected 1.1.1 to before 1.1.1zgAffected 1.0.2 to before 1.0.2zpAffected

References

OpenSSL Advisoryvendor-advisory
3.6.2 git commitpatch
3.5.6 git commitpatch
3.4.5 git commitpatch
3.3.7 git commitpatch
3.0.20 git commitpatch
https://cert-portal.siemens.com/productcert/html/ssa-265688.html
https://cert-portal.siemens.com/productcert/html/ssa-032379.html

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