CVE-2026-28389 Possible NULL Dereference When Processing CMS KeyAgreeRecipientInfo
Attackers can cause a denial of service by sending crafted CMS data to applications using OpenSSL, triggering a NULL pointer dereference.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-28389?
CVE-2026-28389 is a high-severity vulnerability in Openssl Openssl, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-476
Which versions are affected by CVE-2026-28389?
It affects 1 product.
Products include Openssl Openssl.
How do I fix CVE-2026-28389?
Apply the vendor's patch.
Is CVE-2026-28389 being exploited?
There is no known exploitation of CVE-2026-28389 in the wild and no public exploit code.
Other vulnerabilities in Openssl Openssl
Sources
Also known as ALPINE-CVE-2026-28389, AZL-82067, AZL-82097, AZL-82202, BELL-CVE-2026-28389, CLSA-2026-1777547052 and 14 more.