CVE-2026-42841
CVE-2026-42841 is a Cross-site Scripting (XSS) vulnerability in getgrav/grav. O3 Security confirms whether CVE-2026-42841 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Grav: Stored XSS via Markdown media attribute() action in Grav CMS
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
getgrav/gravReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Grav is a file-based Web platform. Prior to 2.0.0-beta.2, an authenticated user with page editing permissions can inject an executable JavaScript event-handler attribute into rendered image HTML through Grav's Markdown media action syntax. The issue is caused by Markdown image query parameters being converted into callable media actions. The public attribute() media method can be reached this way, allowing an editor to set an arbitrary HTML attribute name and value on the generated image element. This vulnerability is fixed in 2.0.0-beta.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getgrav/grav | all versions | 2.0.0-beta.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getgrav/grav. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update getgrav/grav to 2.0.0-beta.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42841 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-42841 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-42841. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-42841 in your dependencies?
O3 detects CVE-2026-42841 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.