Vulnerability in verbb/formie (CVE-2026-52889)
Summary
Vulnerability in verbb/formie (CVE-2026-52889). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 3.1.27 or later.
Original description
The description as published by the source.
Summary
Formie Hidden fields could evaluate request-derived values as Twig during front-end form rendering.
When a Hidden field used a dynamic default value such as HTTP User Agent, Referer URL, Current URL, Query Parameter, or Cookie Value, the value was copied from the incoming request and later passed to Craft’s Twig rendering layer. This allowed an unauthenticated attacker to provide Twig syntax in request-controlled input and have it evaluated server-side when the form was rendered.
Affected Versions
verbb/formie for Craft 5:
- Affected: >= 3.0.0-beta.1, <= 3.1.26
- Patched: 3.1.27
Impact
An unauthenticated attacker could trigger server-side template evaluation by visiting a public form containing a Hidden field configured with a request-derived default value.
Because Craft’s normal Twig environment exposes application objects, this may lead to disclosure of sensitive information, modification of application state, or remote code execution depending on the site configuration and available Twig capabilities.
Technical Details
The issue exists in the Hidden field front-end render path. Request-derived Hidden field defaults were assigned to the field’s defaultValue, then rendered via Twig in Hidden::getFrontEndInputOptions().
The fix ensures Twig rendering is only performed for the custom default option, where the template source is admin-authored. Request-derived default options are now treated as plain strings.
Patches
Update to Formie 3.1.27 or…
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-2026-52889 has been found in verbb/formie.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade verbb/formie to 3.1.27 or later.
If unsure, ask your IT team or search "verbb/formie CVE-2026-52889" on the vendor's site.
CVE-2026-52889 (verbb/formie) — CWE-1336 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 3.1.27 — 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.
A vulnerability (CWE-1336) exists in verbb/formie.
Check the vendor advisory for the affected versions of verbb/formie.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to 3.1.27.
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 'verbb/formie' . 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 'verbb/formie' . | 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
verbb/formie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 verbb/formie to 3.1.27ステージング環境で 3.1.27 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。
Affected packages
References
- package github.com
- web security-advisories@github.com
- web github.com
- web security-advisories@github.com
- web security-advisories@github.com