PT-2026-42591 · Packagist · Twig/Twig
Published
2026-05-21
·
Updated
2026-05-21
CVSS v4.0
8.7
High
| Vector | AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
Description
The
obj.(expr) dynamic-attribute syntax (added in 3.15.0 as the replacement for the deprecated attribute() function) lets the attribute be an arbitrary expression. When the receiver is self (or any {% import %} alias) and the parenthesised expression is a string literal, DotExpressionParser short-circuits to the macro-call path and concatenates the attacker-controlled string into a MacroReferenceExpression name with no identifier validation. MacroReferenceExpression::compile() then emits that name raw into the generated PHP source.An attacker who can supply template source can inject arbitrary PHP into the compiled template and execute it at template-load time, before
checkSecurity() is ever called. This is a complete bypass of SandboxExtension, including a globally-enabled sandbox with an empty SecurityPolicy allowlist.Resolution
The parser now validates that the dynamic attribute resolves to a valid macro identifier before routing through
MacroReferenceExpression, and the macro-reference compiler emits the name through a properly escaped path.Credits
Twig would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.
Exploit
Fix
Code Injection
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Weakness Enumeration
Related Identifiers
Affected Products
Twig/Twig