Cross-Site Scripting (XSS) in OPNsense (CVE-2026-49131)
Summary
Cross-site scripting in OPNsense (CVE-2026-49131). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
OPNsense before 26.1.9 contains a stored cross-site scripting vulnerability that allows authenticated attackers with firewall rule management privileges to inject arbitrary HTML or JavaScript by embedding payloads in the firewall rule description field via the filter API endpoint. The unsanitized description value is persisted and later rendered through the default cell formatter in opnsense_bootgrid.js, which assigns raw cell content to innerHTML, causing injected scripts to execute in the browser of any authenticated user who views the Firewall Rules page, enabling session hijacking or credential theft.
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-2026-49131 has been found in OPNsense.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "OPNsense CVE-2026-49131" on the vendor's site.
CVE-2026-49131 (OPNsense) — CWE-79 / CVSS v3 5.4
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 OPNsense.
Check the vendor advisory for the affected versions of OPNsense.
Severity: Medium (CVSS 5.4/10). 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 'OPNsense' . 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 'OPNsense' . | 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
OPNsense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
- web nvd.nist.gov
- web disclosure@vulncheck.com
- web disclosure@vulncheck.com
- web disclosure@vulncheck.com
- web github.com