CVE-2026-42845
CVE-2026-42845 is a high-severity vulnerability with a CVSS 4.0 base score of 7.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-73.
Key facts
- Severity: High (CVSS 4.0 base score 7.7)
- EPSS exploit prediction: 1% (46th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-29129
- Weakness: CWE-73
- Published:
- Last modified:
Description
The form plugin for Grav adds the ability to create and use forms. Prior to 9.1.0 , there is an unauthenticated page-content overwrite via file upload (GHSA-w4rc-p66m-x6qq). Public form uploads now strip path components from the POST-supplied filename and hard-block page-content extensions (`md`, `yaml`, `yml`, `json`, `twig`, `ini`) regardless of the configurable dangerous-extensions list. A permissive `accept` policy combined with the default `destination: self@` could otherwise let an attacker overwrite the page's own `.md` and pivot to super-admin via a `process: save` action. This vulnerability is fixed in 9.1.0.
Frequently asked questions
- What is CVE-2026-42845?
- The form plugin for Grav adds the ability to create and use forms. Prior to 9.1.0 , there is an unauthenticated page-content overwrite via file upload (GHSA-w4rc-p66m-x6qq). Public form uploads now strip path components from the POST-supplied filename and hard-block page-content extensions (`md`, `yaml`, `yml`, `json`, `twig`, `ini`) regardless of the configurable dangerous-extensions list. A permissive `accept` policy combined with the default `destination: self@` could otherwise let an attacker overwrite the page's own `.md` and pivot to super-admin via a `process: save` action. This vulnerability is fixed in 9.1.0.
- How severe is CVE-2026-42845?
- CVE-2026-42845 has a CVSS 4.0 base score of 7.7, rated high severity.
- Is CVE-2026-42845 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-42845?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-42845 have an EU (EUVD) identifier?
- Yes. CVE-2026-42845 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29129.
- When was CVE-2026-42845 published?
- CVE-2026-42845 was published on 2026-05-11 and last updated on 2026-06-17.
References
- https://github.com/getgrav/grav-plugin-form/commit/48bacc4187e1cff815000e526d5ca2878484867f
- https://github.com/getgrav/grav/security/advisories/GHSA-w4rc-p66m-x6qq
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