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Findings

CVE-2025-35939

Craft CMS External Control of Assumed-Immutable Web Parameter Vulnerability

Published May 7, 2025 · updated Jun 17, 2026 · craftcms craft cms

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.

Timeline

Detection, updates, and resolution for this record.

  1. May 7, 2025 · Catalog

    Detected

    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]'

  2. Jun 2, 2025 · CISA KEV

    Known exploited

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

  3. Jun 23, 2025 · CISA KEV

    Remediation due

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

  4. Jun 17, 2026 · Catalog

    Updated

    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]'

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.

CISA due date Jun 23, 2025

Affected

  • cpe craftcms/craft cmsversion unspecified
  • vendor Craft CMS Craft CMSversion unspecified

Sources

  • CISA KEVCVE-2025-35939

    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.

    cisa.gov
  • CVE.orgCVE-2025-35939

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2025-35939

    30-day exploitation probability 1.3%

    first.org
  • NIST NVDCVE-2025-35939

    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

    nvd.nist.gov

References