CVE-2026-55890
MEDIUM 4.8 PoC AVAILABLE ALL-YEARSGrav is a file-based Web platform. Prior to 2.0.0-rc.9, Grav's incomplete fix for stored XSS through the Markdown media attribute action (CVE-2026-42841) leaves the sibling MediaObjectTrait::style method reachable through the same Markdown excerpt-action pipeline, allowing an editor to save Markdown image style parameters that are written into the rendered img style attribute without sanitization. This issue is fixed in version 2.0.0-rc.9.
Public exploit or PoC code exists. The barrier to attack is reduced — watch closely.
Exploitation likelihood
0.2%chance of exploitation in 30 days · 9th percentile
Impact if exploited
4.8CVSS 3.1 · MEDIUM · CNA
- ConfidentialityLow
- IntegrityLow
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ⚠Privileges: Requires an admin / high-privilege account
- ⚠User interaction: A user must take an action (click / open a file)
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- reference https://github.com/getgrav/grav/security/advisories/GHSA-pmf8-g7c8-7v54
- github-search https://github.com/search?q=%22CVE-2026-55890%22&type=repositories
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-55890/poc.jsonMachine-readable PoC index for this CVE (for automation).For defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-55890/poc.json
Weakness (CWE)
- CWE-79: : Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
All CVSS metrics
- MEDIUM 4.8 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N - MEDIUM 4.8 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N