Showdown vulnerable to Regular Expression Denial of Service (ReDoS) in link/anchor parsing (CVE-2024-1899) | HOL Guard CVE

Medium · CVSS 5.3CVE-2024-1899GHSA-RMMH-P597-PPVV

Showdown vulnerable to Regular Expression Denial of Service (ReDoS) in link/anchor parsing

Answer in brief

CVE-2024-1899 records a Medium severity (CVSS 5.3) vulnerability in Showdown vulnerable to Regular Expression Denial of Service (ReDoS) in link/anchor parsing. The current sources do not mark it as known exploited. The current feed maps showdown (npm). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Feb 26, 2024Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps showdown (npm). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
showdownnpm	>=0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for showdown.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Feb 26, 2024
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

Showdownjs, versions <= 2.1.0, `anchors` subparser used to parse links has a nested regular expression which can lead to denial of service conditions given malicious input.

Quoted source text, attributed separately from HOL analysis.