CVE-2025-35939

Craft CMS stores user-provided content in session files

MEDIUM

5.3

CVSS Score

Published: May 7, 2025 at 10:41 PM UTC

Updated: June 17, 2026 at 09:14 AM UTC

2 products affected across 2 vendorsCraftcmsCraft CMS

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Severity

MEDIUM5.3

Exploitation

CISA KEV

Exploit prediction

EPSS 1%

SSVC

Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score1.3%

EPSS (Exploit Prediction Scoring System) estimates a 1.3% chance this CVE is exploited in the wild within the next 30 days — higher than 71% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

Craft CMS contains an external control of assumed-immutable web parameter vulnerability. This vulnerability could allow an unauthenticated client to introduce arbitrary values, such as PHP code, to a known local file location on the server. This vulnerability could be chained with CVE-2024-58136 as represented by CVE-2025-32432.

Required Action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Ransomware Use

Unknown

Added to KEV

Jun 2, 2025

Remediation Due

Jun 23, 2025

494 days overdue

Notes

https://github.com/craftcms/cms/pull/17220

https://nvd.nist.gov/vuln/detail/CVE-2025-35939

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.