# Grav is Vulnerable to Security Sandbox Bypass with SSTI (Server Side Template Injection)

Advisory record · `GHSA-gjc5-8cfh-653x`

- **Identifiers:** `GHSA-gjc5-8cfh-653x` · `CVE-2025-66299` · `PKSA-83gv-619f-b6h7`
- **State:** Confirmed
- **Severity:** CVSS 8.8 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, 00:36 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.

> Grav CMS versions before 1.8.0-beta.27 are affected by a server-side template injection flaw that bypasses the Twig security sandbox. An attacker needs an account with editor permissions on a page where Twig processing is enabled; by injecting crafted template directives, they can execute arbitrary operating system commands on the server. The fix is to upgrade the getgrav/grav package to 1.8.0-beta.27 or later.

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

- 8.8 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0065, the 51st percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 13:59 UTC: First seen by agentprime
- 31 Oct 2026, 13:59 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-gjc5-8cfh-653x)

## Sources

- [GitHub Advisory Database: GHSA-gjc5-8cfh-653x](https://github.com/advisories/GHSA-gjc5-8cfh-653x)
- [OSV: GHSA-gjc5-8cfh-653x](https://osv.dev/vulnerability/GHSA-gjc5-8cfh-653x)
- <https://github.com/getgrav/grav/security/advisories/GHSA-gjc5-8cfh-653x>
- <https://nvd.nist.gov/vuln/detail/CVE-2025-66299>
- <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-gjc5-8cfh-653x>, 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-gjc5-8cfh-653x/>. Everything for agents: <https://agentprime.io/llms.txt>.