# Backdrop CMS Host Header Injection vulnerability

Advisory record · `GHSA-ffpg-gm3h-4p5p`

- **Identifiers:** `GHSA-ffpg-gm3h-4p5p` · `CVE-2025-63828` · `PKSA-2f77-cwcx-9j4j`
- **State:** Confirmed
- **Severity:** CVSS 6.1 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-601](https://cwe.mitre.org/data/definitions/601.html) · [CWE-644](https://cwe.mitre.org/data/definitions/644.html)
- **Tags:** [Open redirect](https://agentprime.io/advisories/tag/open-redirect.md) · [CWE-644](https://agentprime.io/advisories/tag/cwe-644.md)
- **Published:** 18 Nov 2025
- **Updated:** 20 Nov 2025
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 18 Nov 2025, 18:32 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `backdrop/backdrop` (Packagist): affected `<=1.32.0`; no fixed version yet

## Machine-written summary

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

> Backdrop CMS (backdrop/backdrop) versions up to and including 1.32.0 are affected by a Host Header Injection vulnerability. An attacker can manipulate the Host header in password reset requests, which can redirect users to malicious domains and may enable session hijacking through cookie injection. The source gives few details about the required attacker position or user interaction. No fixed version is listed.

Written 3 Nov 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

- 6.1 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`, from ADP (CISA-ADP)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0023, the 13th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 18 Nov 2025, 18:16 UTC: [Confirmed by NVD](https://nvd.nist.gov/vuln/detail/CVE-2025-63828)
- 31 Oct 2026, 14:26 UTC: First seen by agentprime
- 31 Oct 2026, 14:26 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-ffpg-gm3h-4p5p)

## Sources

- [GitHub Advisory Database: GHSA-ffpg-gm3h-4p5p](https://github.com/advisories/GHSA-ffpg-gm3h-4p5p)
- [OSV: GHSA-ffpg-gm3h-4p5p](https://osv.dev/vulnerability/GHSA-ffpg-gm3h-4p5p)
- <https://nvd.nist.gov/vuln/detail/CVE-2025-63828>
- <https://github.com/backdrop/backdrop>
- <https://github.com/mertdurum06/BackdropCms-1.32.1>
- <https://github.com/mertdurum06/BackdropCms-1.32.1/blob/main/backdropcms_exploit.txt>

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-ffpg-gm3h-4p5p>, 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-ffpg-gm3h-4p5p/>. Everything for agents: <https://agentprime.io/llms.txt>.