Path Traversal in getgrav/grav (CVE-2026-42608)
Summary
Path traversal in getgrav/grav (CVE-2026-42608). Confidential information can be exposed externally. Exploitable via POST /contact. Mitigation: upgrade to 2.0.0-beta.2 or later.
Original description
The description as published by the source.
Vulnerability Report: Grav CMS Unauthenticated Path Traversal & Arbitrary File Write
[ZERO-DAY] Unauthenticated Path Traversal leading to Arbitrary Directory Creation and Configuration Injection
Summary
Grav CMS (v1.7.49.5 and latest development source) is vulnerable to a Zero-Day Path Traversal vulnerability within the FormFlash core component. By manipulating the session_id (passed as __form-flash-id in POST requests), an unauthenticated attacker can traverse the filesystem to create arbitrary directories and write an index.yaml file containing attacker-controlled data.
This vulnerability can lead to unauthorized modification of application behavior, potential data integrity issues, and service disruption in production environments.
Affected Component
- Versions: Confirmed in Grav v1.7.49.5 (latest stable) and the latest development source (March 2026).
- Class:
Grav\Framework\Form\FormFlash - Method:
__construct()/getTmpDir() - Parameter:
session_id(Mapped to__form-flash-idin POST requests)
Vulnerability Details
The FormFlash class is used to persist form data across redirects. It constructs a temporary storage path using the provided session_id. The path construction logic in the latest source:
$folder = $config['folder'] ?? ($this->sessionId ? 'tmp://forms/' . $this->sessionId : '');
$this->folder = $folder && $locator->isStream($folder) ? $locator->findResource($folder, true, true) : $folder;
Lack of sanitization on…
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-2026-42608 has been found in getgrav/grav.
Attackers can target a specific entry point like POST /contact over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 9.1/10.
What to do: upgrade getgrav/grav to 2.0.0-beta.2 or later.
If unsure, ask your IT team or search "getgrav/grav CVE-2026-42608" on the vendor's site.
CVE-2026-42608 (getgrav/grav) — CWE-22 / CVSS v3 9.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /contact / index.yaml / session_id / findResource
Patched: 2.0.0-beta.2 — 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.
Path traversal (CWE-22) exists in getgrav/grav. Attackers reach the vulnerable code path via POST /contact without authentication.
Check the vendor advisory for the affected versions of getgrav/grav. Attack surface: POST /contact / index.yaml / session_id / findResource.
Severity: Critical (CVSS 9.1/10). Confidential information can be exposed externally.
Update to 2.0.0-beta.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /contact requests with malformed payloads or SQL meta-characters. Run grep -r 'getgrav/grav' . 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 'getgrav/grav' . | 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
getgrav/gravを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /contact' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /contactへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade getgrav/grav to 2.0.0-beta.2ステージング環境で 2.0.0-beta.2 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 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against POST /contact on staging to confirm patch closes the vector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 2 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
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com