Twig CVE-2026-46640
HIGH
GHSA-45vw-wh46-2vx8
Lifecycle Timeline
2DescriptionNVD
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.
AnalysisAI
Arbitrary PHP code execution in Twig templating engine versions 3.15.0 through 3.25.x allows attackers who control template source to inject raw PHP into the compiled template via the _self.(<string>) dynamic-attribute macro-reference path, fully bypassing the SandboxExtension. The flaw executes injected code at template-load time, before any SecurityPolicy check runs, rendering even a globally-enabled empty allowlist sandbox ineffective. …
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RemediationAI
Within 24 hours: Identify all systems running Twig 3.15.0-3.25.x and assess which handle untrusted template input. Within 7 days: Implement compensating controls including strict access controls on template sources, disable dynamic template processing features, and apply network isolation for high-risk applications. …
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