CVE-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 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.
do firstUpgrade to a fixed release: 5.7.5, 4.15.3.
Can a WAF block it? No. The vulnerability involves unauthenticated users sending HTTP requests that cause arbitrary content to be stored in session files on the server. The malicious input looks like normal parameters in the request and is not sanitized, so it resembles legitimate traffic and cannot be reliably distinguished by a WAF.
Also consider: patch
Based on an AI reading of the CVE description, and no vendor rule found yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2025-35939 being exploited?
Yes. CVE-2025-35939 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2025-35939?
CVE-2025-35939 is rated Medium with a CVSS score of 5.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2025-35939?
Yes. A fix has been recorded for CVE-2025-35939. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2025-35939 affect?
CVE-2025-35939 affects craftcms:craft_cms. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
- affected< 5.7.5
- affected< 4.15.3
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
cisa ssvc
- exploitation
- active
- automatable
- yes
- technical impact
- partial
Assessed by CISA 6 Jun 2025 (SSVC 2.0.3).
timeline
- 7 May 2025Published
- 2 Jun 2025Added to CISA KEV (exploited in the wild) · 25 days later
- 6 Jun 2025CISA SSVC assessment: exploitation active · 4 days later
- 23 Jun 2025CISA remediation due date (US federal agencies) · 17 days later
- 26 Feb 2026CVE record last updated · 249 days (about 8 months) later
- 2 Nov 2026Analysed by vulneraibility.com · 249 days (about 8 months) later
also known as
- Linkgithub.com /craftcms/cms/pull/17220
- Linkgithub.com /craftcms/cms/releases/tag/4.15.3
- Linkgithub.com /craftcms/cms/releases/tag/5.7.5
- Linkcve.org /CVERecord?id=CVE-2025-35939
- Linkraw.githubusercontent.com /cisagov/CSAF/develop/csaf_files/IT/white/2025/va-25-147-01.json
- Linkcisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-35939
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- OSV: advisory aliases and downstream package versions
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.