CVE-2026-33079
Description
A flaw was found in Mistune, a Markdown parser. This vulnerability, known as Regular Expression Denial of Service (ReDoS), exists in the LINK_TITLE_RE regular expression. A remote attacker can exploit this by providing specially crafted Markdown input, which causes the regular expression engine to engage in catastrophic backtracking. This leads to significant CPU consumption, making applications that use Mistune unresponsive and resulting in a Denial of Service.
Statement
This Important flaw in the Mistune Markdown parser can lead to a denial of service in Red Hat OpenShift AI and Migration Toolkit for Applications. A remote attacker can exploit a Regular Expression Denial of Service (ReDoS) vulnerability by submitting specially crafted Markdown input, causing excessive CPU consumption and rendering affected applications unresponsive. This impact is significant as it directly affects the availability of services that process untrusted Markdown content.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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 (CPU)
Attackers can create crafted inputs that intentionally cause the regular expression to use excessive backtracking in a way that causes the CPU consumption to spike.
Frequently Asked Questions
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