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Medium, CVSS 5.1amended

Grav: Stored XSS via Markdown audio/video media URL

CVE-2026-75831GHSA-6qw9-4vv5-jr97

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (getgrav/grav 2.0.15), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
5.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N · score source
EPSS
  • CVE-2026-75831: 0.35% estimated exploitation activity in the next 30 days; percentile 28.71 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Target: github.com/getgrav/grav Affected resource: Grav\Common\Media\Traits\AudioMediaTrait / VideoMediaTrait sourceParsedownElement() — verified on 2.0.13 (latest stable) and develop HEAD 5a7070f Severity: Medium (~6.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:L/A:N — anchored to the sibling script-XSS advisory CVE-2026-42841, same PR:H / S:C / C:H / I:L) Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation) Summary A Markdown audio or video embed renders its <source element as raw HTML with the media URL concatenated unescaped. The URL fragment is reflected without any encoding, so ) breaks out of <source src="…" and injects arbitrary HTML — including a script-executing <svg onload — into the rendered page. Any user who views the page runs the attacker's JavaScript in their session; a logged-in administrator who views it exposes their same-origin Grav Admin session to the attacker's script. This is the next sink in the media-parameter injection class the…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-6qw9-4vv5-jr97

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-6qw9-4vv5-jr97

Agent brief

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# Patch Next advisory brief: CVE-2026-75831

Advisory: Grav: Stored XSS via Markdown audio/video media URL
IDs: CVE-2026-75831, GHSA-6qw9-4vv5-jr97
Record: https://patchnext.com/advisories/cve-2026-75831 (revision 3, source checked 26 Oct 2026, 14:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getgrav/grav 2.0.15. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getgrav/grav: affected <= 2.0.14; fixed in 2.0.15

## Suggested inspection (read-only)
- Packagist getgrav/grav: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on getgrav/grav.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-6qw9-4vv5-jr97 (OSV record GHSA-6qw9-4vv5-jr97 lists affected ranges: Packagist getgrav/grav >=0 <2.0.15 (fixed))
- Verified: https://github.com/advisories/GHSA-6qw9-4vv5-jr97 (GitHub-reviewed advisory GHSA-6qw9-4vv5-jr97 lists affected ranges: Packagist getgrav/grav >=0 <=2.0.14)

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