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CVE-2025-35939

Craft CMS External Control of Assumed-Immutable Web Parameter

5.3 MEDIUMActively exploited (CISA KEV)EPSS 1.35%
  1. Published7 May 2025
  2. Added to CISA KEV2 Jun 2025
  3. Remediation due23 Jun 2025
Actively exploited (CISA KEV)

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.

Added to KEV: 2 Jun 2025Federal remediation due: 23 Jun 2025

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

Craftcms Craft CMS≥ 5.0.0 < 5.7.5 · < 4.15.3

Remediation

Fixed in
Craftcms Craft CMS≥ 5.7.5

References

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Frequently asked

Is CVE-2025-35939 being actively exploited?

Yes. CVE-2025-35939 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 2 Jun 2025.

How severe is CVE-2025-35939?

CVE-2025-35939 has a CVSS 3.1 base score of 5.3, rated medium. EPSS estimates a 1.35% probability of exploitation.

Which products are affected by CVE-2025-35939?

Affected products include Craftcms Craft CMS.

How do I fix CVE-2025-35939?

Upgrade affected software to a fixed version, for example Craftcms Craft CMS 5.7.5 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-35939 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.