Cross-Site Scripting (XSS) in Mcgill (CVE-2026-35403)
Summary
Cross-site scripting in Mcgill (CVE-2026-35403). Confidential information can be exposed externally. Mitigation: upgrade to 27.0.3 or later.
Original description
The description as published by the source.
LORIS (Longitudinal Online Research and Imaging System) is a self-hosted web application that provides data- and project-management for neuroimaging research. From 15.10 to before 27.0.3 and 28.0.1, there is a potential for a cross-site scripting attack in the survey_accounts module if a user provides an invalid visit label. While the data is properly JSON encoded, the Content-Type header is not set causing the web browser to interpret the payload as HTML, opening the possibility of a cross-site scripting if a user is tricked into following an invalid link. This vulnerability is fixed in 27.0.3 and 28.0.1.
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-2026-35403 has been found in Mcgill.
Confidential information can be exposed externally. CVSS score: 6.5/10.
What to do: upgrade Mcgill to 27.0.3 or later.
If unsure, ask your IT team or search "Mcgill CVE-2026-35403" on the vendor's site.
CVE-2026-35403 (Mcgill) — CWE-79 / CVSS v3 6.5
Attack vector: remote (network-reachable)
Patched: 27.0.3 — 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 Mcgill.
Check the vendor advisory for the affected versions of Mcgill.
Severity: Medium (CVSS 6.5/10). Confidential information can be exposed externally.
Update to 27.0.3.
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 'Mcgill' . 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
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1Identify exposure identify
grep -r 'Mcgill' . | 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
Mcgill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 Mcgill to 27.0.3ステージング環境で 27.0.3 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。
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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。
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov