# Twig: Sandbox \`\_\_toString()\` policy bypass via dynamic mapping keys

Advisory record · `GHSA-5v5v-ww74-355v`

- **Identifiers:** `GHSA-5v5v-ww74-355v` · `CVE-2026-48806` · `PKSA-1tmc-rt7x-12w6`
- **State:** Confirmed
- **Severity:** CVSS 7.1 High
- **Critical:** No
- **Weakness (CWE):** [CWE-693](https://cwe.mitre.org/data/definitions/693.html) · [CWE-863](https://cwe.mitre.org/data/definitions/863.html)
- **Tags:** [Broken access control](https://agentprime.io/advisories/tag/access-control.md) · [CWE-693](https://agentprime.io/advisories/tag/cwe-693.md)
- **Published:** 30 Jun 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 30 Jun 2026, 18:42 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `twig/twig` (Packagist): affected `<3.27.0`; fixed in `3.27.0`

## Machine-written summary

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

> Twig (Packagist twig/twig) versions before 3.27.0 are affected. A sandboxed template author can use an object as a dynamic mapping key so that its \_\_toString() method runs without the sandbox policy being checked, even though direct output of the same object is blocked. The main impact described is unauthorised disclosure of data returned by \_\_toString(). Upgrade to Twig 3.27.0, which fixes the issue.

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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0042, the 36th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 27 May 2026, 13:13 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/twigphp/Twig/security/advisories/GHSA-5v5v-ww74-355v)
- 31 Oct 2026, 14:01 UTC: First seen by agentprime
- 31 Oct 2026, 14:01 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-5v5v-ww74-355v)

## Sources

- [GitHub Advisory Database: GHSA-5v5v-ww74-355v](https://github.com/advisories/GHSA-5v5v-ww74-355v)
- [OSV: GHSA-5v5v-ww74-355v](https://osv.dev/vulnerability/GHSA-5v5v-ww74-355v)
- <https://github.com/twigphp/Twig/security/advisories/GHSA-5v5v-ww74-355v>
- <https://github.com/FriendsOfPHP/security-advisories/blob/master/twig/twig/CVE-2026-48806.yaml>
- <https://github.com/twigphp/Twig>
- <https://github.com/twigphp/Twig/releases/tag/v3.27.0>
- <https://symfony.com/blog/cve-2026-48806-sandbox-tostring-policy-bypass-via-dynamic-mapping-keys>

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-5v5v-ww74-355v>, 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-5v5v-ww74-355v/>. Everything for agents: <https://agentprime.io/llms.txt>.