Cross-Site Scripting (XSS) in CheckUser (CVE-2026-58034)
Summary
Cross-site scripting in CheckUser (CVE-2026-58034). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation CheckUser.
This vulnerability is associated with program files modules/ext.CheckUser.TempAccounts/components/blockConnectedTempAccountsField.Vue.
This issue affects CheckUser: from 1.46.0-rc.0 before 1.46.0.
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-2026-58034 has been found in CheckUser.
Risk of unauthorized operations or information disclosure. CVSS score: 4.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CheckUser CVE-2026-58034" on the vendor's site.
CVE-2026-58034 (CheckUser) — CWE-79 / CVSS v3 4.8
Attack vector: remote (network-reachable)
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 CheckUser.
Check the vendor advisory for the affected versions of CheckUser.
Severity: Medium (CVSS 4.8/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
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 'CheckUser' . 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 'CheckUser' . | 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
CheckUserを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-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。
References
- report phabricator.wikimedia.org
- web nvd.nist.gov
- web github.com