VulnerabilityAnalyzed

CVE-2025-35939

Craft CMS External Control of Assumed-Immutable Web Parameter Vulnerability

KEVMEDIUM 6.9EPSS 1.32%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 23 June 2025). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

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.

CVSS 4.0: 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 1.32% probability · 69th percentile
CISA KEV: Listed 2 June 2025 · due 23 June 2025
Weakness: CWE-472
Affected: craftcms/craft cms
Source: 9119a7d8-5eab-497f-8521-727c672e3725

CISA notes

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. https://github.com/craftcms/cms/pull/17220 ; https://nvd.nist.gov/vuln/detail/CVE-2025-35939

References

https://github.com/craftcms/cms/pull/17220Patch
https://github.com/craftcms/cms/releases/tag/4.15.3Release Notes
https://github.com/craftcms/cms/releases/tag/5.7.5Release Notes
https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2025/va-25-147-01.jsonThird Party Advisory
https://www.cve.org/CVERecord?id=CVE-2025-35939VDB Entry
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-35939US Government Resource

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.