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.
- Exploited in the wild
- Since 2 Jun 2025
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
Which versions are affected by CVE-2025-35939?
4 open source packages ship an affected version, including craftcms/cms. It affects 1 product.
| Package | 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 include 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.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
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
Sources
Also known as GHSA-7vrx-9684-xrf2.