CVE-2026-59710 showdown - Stored XSS via Unescaped Table Header ID Attribute Injection
Attackers can inject malicious scripts via markdown table headers, leading to stored XSS when rendered with default settings.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-59710?
CVE-2026-59710 is a medium-severity cross-site scripting vulnerability in showdown, published on 6 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
showdown contains a stored cross-site scripting vulnerability in the parseHeaders function of src/subParsers/makehtml/tables.js that fails to properly escape table header ID attributes. Attackers can inject arbitrary HTML and script-executing SVG elements through double-quote characters in markdown table headers, achieving stored XSS when untrusted markdown is rendered with the default github flavor configuration.
Weakness: CWE-79
Which versions are affected by CVE-2026-59710?
2 open source packages ship an affected version, including showdown.
| Package | Affected | Fixed in |
|---|---|---|
showdown npm | All versions to 2.1.0 | None |
showdown npm | All versions to 2.1.0 | None |
How do I fix CVE-2026-59710?
Apply the vendor's patch.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-59710 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59710 exists.
Sources
Also known as GHSA-22g5-r2x5-97cx, MINI-2fhh-8m2v-f3vv, MINI-4rmr-2742-mpf5, MINI-h37w-3g9v-9g8q, MINI-qm85-wcc2-329m, MINI-rcx3-rfv5-3223 and 1 more.