NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
📦
📦 npm
Not in CISA KEV
MEDIUM severity

CVE-2020-28455 — markdown-it-toc

MEDIUM

CVE-2020-28455 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in markdown-it-toc. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

markdown-it-toc Cross-site Scripting due to title of generated toc and contents of header not being escaped

Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.6%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs50th percentile — riskier than 50% of all scored CVEsHighest risk
0.00%0.37%0.74%1.11%0.2%0.6%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

24other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
markdown-it-tocnpm
4Kdownloads / week

Description

This affects all versions of package markdown-it-toc. The title of the generated toc and the contents of the header are not escaped.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npmmarkdown-it-tocall versionsNo fix

Affected Products

1 product · 1 configurations
Application
markdown-it-tocmarkdown-it-toc_project
all
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

This affects all versions of package markdown-it-toc. The title of the g…

security.snyk.ioNVDAug 2022

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for markdown-it-toc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    The records we use list no patched version of markdown-it-toc for CVE-2020-28455. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

This affects all versions of package markdown-it-toc. The title of the generated toc and the contents of the header are not escaped.
O3 Security · Impact-Aware SCA

Is CVE-2020-28455 in your dependencies?

Find it across npm, including transitive dependencies.

Scan my dependencies How O3 SCA works
CVE-2020-28455: markdown-it-toc (Medium 6.1)