Cross-Site Scripting (XSS) in Outline (CVE-2026-43887)
Summary
Cross-site scripting in Outline (CVE-2026-43887). Confidential information can be exposed externally. Mitigation: upgrade to 1.7.0 or later.
Original description
The description as published by the source.
Outline is a service that allows for collaborative documentation. From 0.84.0 to 1.6.1, the Outline comment section permits users to mention other users; however, the backend does not validate or sanitize the href attribute associated with these mentions. As a result, potentially dangerous protocols (e.g., javascript:) are not filtered, introducing a risk of client-side code execution. This vulnerability is fixed in 1.7.0.
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-2026-43887 has been found in Outline.
Confidential information can be exposed externally. CVSS score: 7.3/10.
What to do: upgrade Outline to 1.7.0 or later.
If unsure, ask your IT team or search "Outline CVE-2026-43887" on the vendor's site.
CVE-2026-43887 (Outline) — CWE-79 / CVSS v3 7.3
Attack vector: remote (network-reachable)
Patched: 1.7.0 — 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 Outline.
Check the vendor advisory for the affected versions of Outline.
Severity: High (CVSS 7.3/10). Confidential information can be exposed externally.
Update to 1.7.0.
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 'Outline' . 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 'Outline' . | 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
Outline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 Outline to 1.7.0ステージング環境で 1.7.0 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。
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov