CVE-2026-61453 PUBLISHED

Grav before 2.0.1 XSS via Twig String Concatenation

Assigner: VulnCheck
Reserved: 09.07.2026 Published: 15.07.2026 Updated: 15.07.2026

Grav v2.0.0 contains a cross-site scripting vulnerability (fixed in 2.0.1). The XSS blueprint validator (Security::detectXss()) runs on raw page content before Twig processing. When Twig content processing is enabled (twig_content.process_enabled: true), an attacker with page-write API permission can use Twig's string concatenation operator (~) to dynamically construct event handler names, dangerous tag names, or dangerous protocols at render time (e.g. {% set x = "on" ~ "error" %}). The validator sees only the harmless Twig expression and allows the content, but after Twig rendering the output (rendered via {{ page.content|raw }}) contains an active payload such as <img src=1 onerror=alert(1)>, executing arbitrary JavaScript in visitors' browsers.

Metrics

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CVSS Score: 5.1

Product Status

Vendor getgrav
Product grav
Versions Default: unaffected
  • affected from 0 to 2.0.1 (excl.)
  • Version 2.0.1 is unaffected

Credits

  • alienkeric reporter
  • gemstone-source reporter

References

Problem Types

  • Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CWE