CVE-2026-28389
Description
A flaw was found in OpenSSL. A remote attacker could exploit this by sending a specially crafted Cryptographic Message Syntax (CMS) EnvelopedData message with KeyAgreeRecipientInfo. This vulnerability arises because the software attempts to process an optional field without verifying its existence, leading to a NULL pointer dereference. This can result in a Denial of Service (DoS) for applications that handle untrusted CMS data.
Statement
This Low impact flaw affects applications processing Cryptographic Message Syntax (CMS) data, specifically crafted CMS EnvelopedData messages with KeyAgreeRecipientInfo. A NULL pointer dereference can occur if the optional parameters field of KeyEncryptionAlgorithmIdentifier is missing, leading to a Denial of Service. Red Hat products are vulnerable if they call CMS_decrypt() or PKCS7_decrypt() on untrusted input, such as in S/MIME processing or CMS-based protocols.
Mitigation
To mitigate this issue, avoid processing untrusted CMS EnvelopedData messages with KeyAgreeRecipientInfo. Restrict network access to services that process CMS data from untrusted sources. If possible, configure applications to only accept CMS data from trusted origins. This operational control helps reduce exposure to the vulnerability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | 7.5 | 7.5 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | None |
| Integrity Impact | None | None | None |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
