Privilege Escalation in getgrav/grav (CVE-2026-42844)
Summary
Vulnerability in getgrav/grav (CVE-2026-42844). Successful exploitation can lead to full system takeover. Exploitable via POST /api/v1/auth/token. Mitigation: upgrade to 2.0.0-beta.4 or later.
Original description
The description as published by the source.
Summary
In Grav 2.0.0-beta.2, a low-privileged authenticated API user with api.media.write can abuse /api/v1/blueprint-upload to write an arbitrary YAML file into user/accounts/, then log in as the newly created account with api.super privileges.
This results in full administrative compromise of the Grav API.
Details
The vulnerability is located in the API plugin's blueprint upload flow:
user/plugins/api/classes/Api/ApiRouter.php:261user/plugins/api/classes/Api/Controllers/BlueprintUploadController.php:32-45user/plugins/api/classes/Api/Controllers/BlueprintUploadController.php:102-114user/plugins/api/classes/Api/Controllers/BlueprintUploadController.php:271-308user/plugins/api/classes/Api/Controllers/BlueprintUploadController.php:407-417user/plugins/api/classes/Api/Controllers/AuthController.php:41-55
The issue exists because /api/v1/blueprint-upload accepts caller-controlled destination and scope values and uses them to resolve the final filesystem write target.
When the request uses:
destination=self@:scope=users/anything
The server resolves the write target to the shared account directory:
user/accounts/
The upload handler then writes the supplied file directly into that directory and does not block YAML account files. Because Grav accepts account YAML files and supports a plaintext password: field on first login, an attacker can create a fully functional administrator account with `api.su…
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-2026-42844 has been found in getgrav/grav.
Attackers can target a specific entry point like POST /api/v1/auth/token over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade getgrav/grav to 2.0.0-beta.4 or later.
If unsure, ask your IT team or search "getgrav/grav CVE-2026-42844" on the vendor's site.
CVE-2026-42844 (getgrav/grav) — CWE-269 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/v1/auth/token / POST /api/v1/blueprint-upload / GET /api/v1/system/info / api.media.write
Patched: 2.0.0-beta.4 — 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-269) exists in getgrav/grav. Attackers reach the vulnerable code path via POST /api/v1/auth/token.
Check the vendor advisory for the affected versions of getgrav/grav. Attack surface: POST /api/v1/auth/token / POST /api/v1/blueprint-upload / GET /api/v1/system/info / api.media.write.
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.
Update to 2.0.0-beta.4.
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 /api/v1/auth/token 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 /api/v1/auth/token' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/v1/auth/token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.4ステージング環境で 2.0.0-beta.4 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 /api/v1/auth/token 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
- exploit github.com
- package github.com
- web github.com
- web github.com