Vulnerability in @ckeditor/ckeditor5-markdown-gfm (CVE-2021-21254)
Summary
Vulnerability in @ckeditor/ckeditor5-markdown-gfm (CVE-2021-21254). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 25.0.0 or later.
Original description
The description as published by the source.
CKEditor 5 is an open source rich text editor framework with a modular architecture. The CKEditor 5 Markdown plugin (@ckeditor/ckeditor5-markdown-gfm) before version 25.0.0 has a regex denial of service (ReDoS) vulnerability. The vulnerability allowed to abuse link recognition regular expression, which could cause a significant performance drop resulting in browser tab freeze. It affects all users using CKEditor 5 Markdown plugin at version <= 24.0.0. The problem has been recognized and patched. The fix will be available in version 25.0.0.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2021-21254 has been found in @ckeditor/ckeditor5-markdown-gfm.
Risk of unauthorized operations or information disclosure.
What to do: upgrade @ckeditor/ckeditor5-markdown-gfm to 25.0.0 or later.
If unsure, ask your IT team or search "@ckeditor/ckeditor5-markdown-gfm CVE-2021-21254" on the vendor's site.
CVE-2021-21254 (@ckeditor/ckeditor5-markdown-gfm) — CWE-400
Attack vector: remote (network-reachable) / no user interaction
Patched: 25.0.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-400) exists in @ckeditor/ckeditor5-markdown-gfm.
Check the vendor advisory for the affected versions of @ckeditor/ckeditor5-markdown-gfm.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 25.0.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r '@ckeditor/ckeditor5-markdown-gfm' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r '@ckeditor/ckeditor5-markdown-gfm' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
@ckeditor/ckeditor5-markdown-gfmを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade @ckeditor/ckeditor5-markdown-gfm to 25.0.0ステージング環境で 25.0.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web npmjs.com
- web npmjs.com