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Advisory record · GHSA-q2j8-x8hf-63ch

Grav: Single invalid UTF-8 byte disables every rule in Security::detectXss(), bypassing the page-content XSS safety gate

CVSS 5.1 MediumEPSS 0.0026 · 17th percentile

Published by the GitHub Advisory Database at 17 Sept 2026, 20:44 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
getgrav/gravPackagist<2.0.142.0.14
Identifiers
GHSA-q2j8-x8hf-63ch · CVE-2026-75834 · PKSA-ht1d-wm6t-8sdj
Weakness (CWE)
CWE-79
Tags
Published
17 Sept 2026
Updated
17 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Grav versions before 2.0.14 (getgrav/grav on Packagist) are affected. In the XSS detection function Security::detectXss(), a single invalid UTF-8 byte anywhere in a field value makes every pattern check fail silently, so the content is treated as safe and saved unchanged. An attacker with a page-editing account that lacks super-admin rights, and who can submit a raw non-JSON request, could store JavaScript that runs in the browser of any visitor, including a super-admin. Upgrade to Grav 2.0.14, which contains the fix.

Written 31 Oct 2026.

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

ScoreRatingCVSSVectorSource
5.1 Medium 4.0 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 CNA (VulnCheck)
  • CISA KEV Not listed.
  • EPSS 0.0026, the 17th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 13:55 UTC First seen by agentprime
  2. 31 Oct 2026, 13:55 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.