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CVE-2026-23891
Cross-Site Scripting (XSS) in decidim-core (CVE-2026-23891)
Summary
cross-site scripting in decidim-core (CVE-2026-23891). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to `0.30.5` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-23891** has been found in decidim-core.
Risk of unauthorized operations or information disclosure. CVSS score: ?/10.
What to do: upgrade decidim-core to **0.30.5** or later.
If unsure, ask your IT team or search "decidim-core CVE-2026-23891" on the vendor's site.
CVE-2026-23891 (decidim-core) — CWE-79 /
Patched: `0.30.5` — 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.
❓ What is the problem
**Cross-site scripting (XSS)** (CWE-79) exists in decidim-core.
📍 Affected scope
decidim-core — .
🔥 Severity
Severity: ?. Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **0.30.5**.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'decidim-core' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'decidim-core' . | 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 `decidim-core` を grep し、稼働しているサービス・バージョンを把握する。
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6Apply patch patch
Upgrade decidim-core to 0.30.5ステージング環境で 0.30.5 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
rubygems
decidim-core
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.30.5"}]}]
References
- web https://github.com/decidim/decidim/security/advisories/GHSA-fc46-r95f-hq7g
- web https://github.com/decidim/decidim/releases/tag/v0.30.5
- web https://github.com/decidim/decidim/releases/tag/v0.31.1
- web https://nvd.nist.gov/vuln/detail/CVE-2026-23891
- web https://github.com/rubysec/ruby-advisory-db/blob/master/gems/decidim-core/CVE-2026-23891.yml
- web https://github.com/advisories/GHSA-fc46-r95f-hq7g