CVE-2026-54876
Description
A flaw was found in OpenSSL. A malicious TLS (Transport Layer Security) server can exploit this vulnerability by sending a specially crafted OCSP (Online Certificate Status Protocol) response during the X.509 certificate chain verification process. This can lead to a memory leak in client applications that have enabled OCSP response checking. Repeated connections to a malicious server could exhaust the client's memory, ultimately resulting in a Denial of Service (DoS).
Statement
This vulnerability is rated Important because a malicious TLS server can cause memory exhaustion and denial of service in a long-running client. Exploitation requires the client application to enable OCSP response checking and process a crafted OCSP response from the server. Exposure therefore depends on the application’s configuration.
Mitigation
No broadly applicable mitigation is available. If an affected client application provides a configuration setting for OCSP response checking, operators can temporarily disable it where their certificate revocation policy permits. This blocks the vulnerable response-checking path but removes OCSP-based revocation checks. Clients that must keep OCSP response checking enabled remain exposed.
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 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: 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: Resource Consumption (Other); DoS: Resource Consumption (Memory); DoS: Resource Consumption (CPU)
An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Frequently Asked Questions
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