CVE-2026-40890
Description
A flaw was found in github.com/gomarkdown/markdown, a Go library for parsing Markdown text and rendering as HTML. A remote attacker could exploit this vulnerability by providing a specially crafted malformed input. Specifically, input containing a '<' character not followed by a '>' character, when processed by the SmartypantsRenderer, can lead to an out-of-bounds read or a panic. This can result in a denial of service (DoS) for the application, making it unavailable to legitimate users.
Statement
This is an Important denial of service flaw affecting Red Hat products that utilize the github.com/gomarkdown/markdown library. The vulnerability occurs when the SmartypantsRenderer processes specially crafted malformed Markdown input containing an unclosed '<' character, leading to an out-of-bounds read or application panic. A successful exploitation may lead the application using the library unavailable.
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)
Other
Technical Impact: Varies by Context
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