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Medium, CVSS 6.9Exploited · CISA KEV

Craft CMS stores arbitrary content provided by unauthenticated users in session files

CVE-2025-35939GHSA-7vrx-9684-xrf2

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (craftcms/cms 5.7.5, 4.15.3), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Packagist craftcms/cms

    Affected
    >= 5.0.0-alpha.1, < 5.7.5< 4.15.3
    Fixed in
    5.7.5, 4.15.3

Sources

Severity and exploitation
Exploitation
Confirmed: listed in the CISA Known Exploited Vulnerabilities catalog.
CVSS 4.0
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/E:A · score source
EPSS
  • CVE-2025-35939: 1.35% estimated exploitation activity in the next 30 days; percentile 71.52 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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[sessionvalue], where [sessionvalue] 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.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-7vrx-9684-xrf2

Agent brief

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# Patch Next advisory brief: CVE-2025-35939

Advisory: Craft CMS stores arbitrary content provided by unauthenticated users in session files
IDs: CVE-2025-35939, GHSA-7vrx-9684-xrf2
Record: https://patchnext.com/advisories/cve-2025-35939 (revision 1, source checked 26 Oct 2026, 14:34 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: confirmed: listed in the CISA Known Exploited Vulnerabilities catalog.
Vendor response: Vendor fix available; fixed versions by package: craftcms/cms 5.7.5, 4.15.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist craftcms/cms: affected >= 5.0.0-alpha.1, < 5.7.5; < 4.15.3; fixed in 5.7.5, 4.15.3

## Suggested inspection (read-only)
- Packagist craftcms/cms: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on craftcms/cms.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (CISA added CVE-2025-35939 to the Known Exploited Vulnerabilities catalog on 2025-06-02.)
- Verified: https://github.com/advisories/GHSA-7vrx-9684-xrf2 (GitHub-reviewed advisory GHSA-7vrx-9684-xrf2 lists affected ranges: Packagist craftcms/cms >=5.0.0-alpha.1 =0 <4.15.3)

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