Cross-Site Scripting (XSS) in craftcms/cms (CVE-2026-55790)
Summary
Cross-site scripting in craftcms/cms (CVE-2026-55790). Risk of unauthorized operations or information disclosure. Exploitable via CraftSupportWidget.js. Mitigation: upgrade to 4.17.16 or later.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database 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-2026-55790 has been found in craftcms/cms.
Attackers can target a specific entry point like CraftSupportWidget.js over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade craftcms/cms to 4.17.16 or later.
If unsure, ask your IT team or search "craftcms/cms CVE-2026-55790" on the vendor's site.
CVE-2026-55790 (craftcms/cms) — CWE-79
Attack surface: CraftSupportWidget.js / FeedbackScreen.getSearchResultText / result.title / innerHTML
Patched: 4.17.16 — 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.
Cross-site scripting (XSS) (CWE-79) exists in craftcms/cms. Attackers reach the vulnerable code path via CraftSupportWidget.js.
Check the vendor advisory for the affected versions of craftcms/cms. Attack surface: CraftSupportWidget.js / FeedbackScreen.getSearchResultText / result.title / innerHTML.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 4.17.16.
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 'craftcms/cms' . 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
-
1Identify exposure identify
grep -r 'craftcms/cms' . | 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
craftcms/cms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 craftcms/cms to 4.17.16ステージング環境で 4.17.16 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
- patch github.com
- web github.com