# CVE-2025-35939: Craft CMS External Control of Assumed-Immutable Web Parameter

> Unauthenticated attackers can inject arbitrary PHP code into session files via unsanitized return URLs, potentially leading to remote code execution.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Yes, since 2 Jun 2025 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 May 2025
- **Updated:** 26 Feb 2026
- **Also known as:** GHSA-7vrx-9684-xrf2

## What is CVE-2025-35939?

CVE-2025-35939 is a medium-severity code injection vulnerability in Craftcms Craft Cms, published on 7 May 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Craft CMS stores arbitrary content provided by unauthenticated users in session files. This content could be accessed and executed, possibly using an independent vulnerability. Craft CMS redirects requests that require authentication to the login page and generates a session file on the server at '/var/lib/php/sessions'. Such session files are named 'sess_[session_value]', where '[session_value]' is provided to the client in a 'Set-Cookie' response header. Craft CMS stores the return URL requested by the client without sanitizing parameters. Consequently, an unauthenticated client can introduce arbitrary values, such as PHP code, to a known local file location on the server. Craft CMS versions 5.7.5 and 4.15.3 have been released to address this issue.

Weakness: CWE-472 (External Control of Assumed-Immutable Web Parameter)

## Which versions are affected by CVE-2025-35939?

4 open source packages ship an affected version, including craftcms/cms. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `craftcms/cms` | Packagist | All versions | 4.15.3 |
| `craftcms/cms` | Packagist | All versions | 4.15.3 |
| `craftcms/cms` | Packagist | From 5.0.0-alpha.1 | 5.7.5 |
| `craftcms/cms` | Packagist | From 5.0.0-alpha.1 | 5.7.5 |

Products: Craftcms Craft Cms.

## How do I fix CVE-2025-35939?

Upgrade craftcms/cms to a fixed version for your release line: 4.15.3 or 5.7.5. US federal agencies must fix it by 23 Jun 2025.

## Is CVE-2025-35939 being exploited?

Yes. Attackers have exploited CVE-2025-35939 in the wild since at least 2 Jun 2025.

## Other vulnerabilities in Craftcms Craft Cms

- [CVE-2025-32432](https://insights.sbomify.com/CVE-2025-32432/): Craft CMS Code Injection (critical 10.0, exploited in the wild)
- [CVE-2024-56145](https://insights.sbomify.com/CVE-2024-56145/): Craft CMS Code Injection (critical 9.3, exploited in the wild)
- [CVE-2025-23209](https://insights.sbomify.com/CVE-2025-23209/): Craft CMS Code Injection (high 8.1, exploited in the wild)
- [CVE-2023-41892](https://insights.sbomify.com/CVE-2023-41892/): Craft CMS Remote Code Execution vulnerability (critical 10.0)
- [CVE-2021-27903](https://insights.sbomify.com/CVE-2021-27903/): Craft CMS Remote Code Injection (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-35939 and fix it if it is affected.

What it is: CVE-2025-35939 is a medium-severity code injection vulnerability in Craftcms Craft Cms, published on 7 May 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2025-35939 in the wild since at least 2 Jun 2025.

Affected packages and fixed versions:
- craftcms/cms (Packagist): affected all versions; fixed in 4.15.3
- craftcms/cms (Packagist): affected all versions; fixed in 4.15.3
- craftcms/cms (Packagist): affected from 5.0.0-alpha.1; fixed in 5.7.5
- craftcms/cms (Packagist): affected from 5.0.0-alpha.1; fixed in 5.7.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-35939/ (Markdown: https://insights.sbomify.com/CVE-2025-35939/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-35939
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-35939
- OSV: https://osv.dev/vulnerability/CVE-2025-35939

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-35939/
Summaries are generated and may contain mistakes; the official description above is the record.