Vulnerability in markdown-it (CVE-2026-48988)
Summary
Vulnerability in markdown-it (CVE-2026-48988). Risk of unauthorized operations or information disclosure. Exploitable via token.content. Mitigation: upgrade to 14.2.0 or later.
Original description
The description as published by the source.
markdown-it is a Markdown parser. Versions 14.1.1 and below contain a denial-of-service vulnerability when typographer: true is enabled, due to quadratic (O(n^2)) processing in the smartquotes rule. The issue stems from repeatedly modifying strings with replaceAt(), which performs O(n) slicing and concatenation per quote character. This can cause excessive CPU consumption when parsing quote-heavy, user-supplied markdown and may let attackers degrade or disrupt service availability. Although typographer is disabled by default, many production apps enable it for smart typography, making the issue relevant. This issue has been fixed in version 14.2.0.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
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-2026-48988 has been found in markdown-it.
Attackers can target a specific entry point like token.content over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade markdown-it to 14.2.0 or later.
If unsure, ask your IT team or search "markdown-it CVE-2026-48988" on the vendor's site.
CVE-2026-48988 (markdown-it) — CWE-400 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: token.content / typographer / false
Patched: 14.2.0 — 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 markdown-it. Attackers reach the vulnerable code path via token.content without authentication.
Check the vendor advisory for the affected versions of markdown-it. Attack surface: token.content / typographer / false.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 14.2.0.
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 'markdown-it' . 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 'markdown-it' . | 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
markdown-it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 markdown-it to 14.2.0ステージング環境で 14.2.0 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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-48988 node-markdown-it
- Ubuntu UBUNTU-CVE-2026-48988 node-markdown-it
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- web github.com