Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Grav versions 2.0.0-rc.9 up to (but not including) 2.0.0 are affected by stored CSS injection in Markdown image media actions, where the resize() action writes unvalidated width and height values directly into an image's style attribute. A user who can edit page Markdown can store a crafted image URL that adds extra CSS declarations, which are rendered for higher-privileged users viewing the page or admin preview; the source describes this as overlay and content-manipulation risk, not JavaScript execution. Upgrade to Grav 2.0.0.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 4.8 | Medium | 4.0 | CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N | CNA (VulnCheck) |
- CISA KEV Not listed.
- EPSS 0.0027, the 18th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 13:56 UTC First seen by agentprime
- 31 Oct 2026, 13:56 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-ffmg-hfvg-jhg9
- OSV: GHSA-ffmg-hfvg-jhg9
- github.com/getgrav/grav/security/advisories/GHSA-ffmg-hfvg-jhg9
- nvd.nist.gov/vuln/detail/CVE-2026-58657
- github.com/getgrav/grav/commit/6582166173bb8eb5869d96aea384e0e73777c94c
- github.com/getgrav/grav/commit/e03d29aa0d3ece16d73c1ffccfa78df8bf5f28b8
- github.com/getgrav/grav
- www.vulncheck.com/advisories/grav-stored-css-injection-via-markdown-image-resize-action