# Grav is vulnerable to RCE via SSTI through Twig Sandbox Bypass

Advisory record · `GHSA-662m-56v4-3r8f`

- **Identifiers:** `GHSA-662m-56v4-3r8f` · `CVE-2025-66294` · `PKSA-cyrn-zc8g-f5mw`
- **State:** Confirmed
- **Severity:** CVSS 8.7 High
- **Critical:** No
- **Weakness (CWE):** [CWE-94](https://cwe.mitre.org/data/definitions/94.html) · [CWE-1336](https://cwe.mitre.org/data/definitions/1336.html)
- **Tags:** [Code injection](https://agentprime.io/advisories/tag/code-injection.md)
- **Published:** 2 Dec 2025
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 2 Dec 2025, 01:25 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `getgrav/grav` (Packagist): affected `<1.8.0-beta.27`; fixed in `1.8.0-beta.27`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The Grav CMS (getgrav/grav, Packagist) is affected in versions before 1.8.0-beta.27. A server-side template injection flaw in the Twig sanitization method cleanDangerousTwig lets an authenticated user with editor permissions run arbitrary commands on the server through a form's process section, and the advisory says an unauthenticated visitor may also be able to exploit it when an existing form passes user input through evaluate_twig. Upgrade to 1.8.0-beta.27 or later, which is listed as the fixed version.

Written 31 Oct 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 8.7 High, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.030, the 87th percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:03 UTC: First seen by agentprime
- 31 Oct 2026, 14:03 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-662m-56v4-3r8f)

## Sources

- [GitHub Advisory Database: GHSA-662m-56v4-3r8f](https://github.com/advisories/GHSA-662m-56v4-3r8f)
- [OSV: GHSA-662m-56v4-3r8f](https://osv.dev/vulnerability/GHSA-662m-56v4-3r8f)
- <https://github.com/getgrav/grav/security/advisories/GHSA-662m-56v4-3r8f>
- <https://nvd.nist.gov/vuln/detail/CVE-2025-66294>
- <https://github.com/getgrav/grav/commit/e37259527d9c1deb6200f8967197a9fa587c6458>
- <https://github.com/getgrav/grav>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-662m-56v4-3r8f>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-662m-56v4-3r8f/>. Everything for agents: <https://agentprime.io/llms.txt>.