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OpenSSL NULL pointer dereference in KeyAgreeRecipientInfo CMS EnvelopedData processing causes denial of service

Last refreshed2026-09-30

Status: UPDATED  |  Advisory ID: CVE-2026-28389

Key Details

CVECVE-2026-28389
CVSS Score / Version7.5 (High) / CVSS v3.1
Updated2026-07-24
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Proseattack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is unchanged; confidentiality impact is none; integrity impact is none; availability impact is high.
Affected productsopenssl openssl
Classified asCWE-476 (NULL Pointer Dereference)

Affected Products, Subsystems & Sectors

VendorProductAffected VersionsPatch Status
opensslopenssl
SubsystemsGeneral OT
SectorsMultiple

What to Know

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. (NVD)

What to Do

Monitor openssl's web page for any future patch releases. See vendor advisory link below.

References

SourceReference
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-28389
CVEhttps://www.cve.org/CVERecord?id=CVE-2026-28389
Vendor advisoryhttps://openssl-library.org/news/secadv/20260407.txt