CVE-2026-28390
Description
A flaw was found in OpenSSL. A remote attacker could exploit this vulnerability by sending a specially crafted Cryptographic Message Syntax (CMS) EnvelopedData message. During the processing of a KeyTransportRecipientInfo with RSA-OAEP encryption, the system attempts to access an optional parameter field without first verifying its presence. This leads to a NULL pointer dereference, which can cause applications processing the attacker-controlled CMS data to crash, resulting in a Denial of Service (DoS).
Statement
This CVE has been rated as moderate by redhat because the vulnerability is limited to a denial-of-service condition caused by a NULL pointer dereference in OpenSSL CMS processing, without evidence of memory corruption or code execution, furthermore the Affected functionality is niche. The vulnerable path requires: CMS/S/MIME processing, specifically CMS_decrypt(), with RSA-OAEP KeyTransportRecipientInfo. Many OpenSSL consumers never use CMS APIs, never process S/MIME, or do not decrypt attacker-controlled CMS objects. So exposure is far narrower than a generic TLS parsing vulnerability.
Mitigation
Applications that process Cryptographic Message Syntax (CMS) EnvelopedData messages should be configured to only accept input from trusted sources. Restricting network access to services that process untrusted CMS data can also reduce exposure to this Denial of Service 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 | 7.5 | 7.5 | 7.5 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | 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:L/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
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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