Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2025-35939

Craft CMS stores user-provided content in session files

Craft / CMS · affected before 5.7.5

Watch CVE-2025-35939 Browse KEV feed
Severity
CVSS 6.9 · Medium
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
1.3%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2025-35939 is an unauthenticated Craft CMS stores user-provided content in session files.

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

Craft / CMS affected before 5.7.5.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

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

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.

Craft Affected
CMS
Before 5.7.5 Before 4.15.3
Craft Unaffected
CMS
5.7.5 4.15.3
Published
07 May 2025
Exploitation Reported
01 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

php cisa

CVE References

  • CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2025-35939
  • url github.com · CVE Record https://github.com/craftcms/cms/pull/17220
  • url github.com · CVE Record https://github.com/craftcms/cms/releases/tag/4.15.3
  • url github.com · CVE Record https://github.com/craftcms/cms/releases/tag/5.7.5
  • url raw.githubusercontent.com · CVE Record https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/...

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CVE

Recorded 01 Jun 2026

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
CVE First 2026-06-01 10:31 UTC
CISA 2026-06-02 14:07 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

6.9 Medium

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

1.3%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

External Control of Assumed-Immutable Web Parameter CWE-472

All CVSS Scores

CVSS v4.0 6.9 Medium

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

CVSS v3.1 5.3 Medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Timeline

From disclosure to observed exploitation

  1. 14:07 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  2. 10:31 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  3. 22:41 UTC

    CVE published

    Vulnerability disclosed publicly

  4. 20:57 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2025-35939

Sample API response 
{
  "cve_id": "CVE-2025-35939",
  "confidence": "Confirmed",
  "cvss_score": 6.9,
  "cvss_estimated": false,
  "epss_score": 0.01349,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}