NULL pointer dereference in OpenSSL

CVE-2026-28389

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.024 (83.6th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 84th percentile — 83.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-28389: rose from 0.008 to 0.024.

EPSS over last 30 days · oldest: 0.008 · newest: 0.024 · change: +0.016

Affected products

  • OpenSSL — versions 3.6.0, 3.5.0, 3.4.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-28389?
CVE-2026-28389 is a high-severity vulnerability in OpenSSL, classified under NULL Pointer Dereference. CVSS score: 7.5/10. Published 2026-04-07.
How severe is CVE-2026-28389?
High severity. CVSS v3 base score is 7.5 out of 10.