CVE-2026-48806 — twig
Fix: twigphp/Twig@9ff4101CVE-2026-48806 is a CWE-693 vulnerability in twig/twig. A fix is available for twig/twig — see the affected versions and patch details below.
Twig: Sandbox `__toString()` policy bypass via dynamic mapping keys
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-48806.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
twig/twigReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Description
This is a residual bypass of CVE-2026-47732 / GHSA-pr2w-4gpj-cpq4 left after the initial fix for unguarded __toString() calls.
In 3.26.0 the sandbox visitor was extended to wrap every child node that its parent will string-coerce at runtime with CheckToStringNode, gated by the new CoercesChildrenToStringInterface. ArrayExpression did not implement the interface for its mapping keys: when a dynamic key expression resolves to a Stringable object, ArrayExpression::compile() emits a raw (string) cast (via StringCastUnary for ContextVariable keys, and no cast at all for richer key expressions). PHP then invokes __toString() directly, without ever calling SandboxExtension::ensureToStringAllowed().
A sandboxed template author can therefore trigger __toString() on any object reachable in the render context by using it as a dynamic mapping key, for example:
{% set arr = {(obj): "value"} %}
Direct output of the same object is correctly blocked, which makes this a clear policy enforcement gap. The reliable demonstrated impact is unauthorised disclosure of data returned by __toString().
Resolution
ArrayExpression now declares its dynamic mapping keys as string-coercion sites through CoercesChildrenToStringInterface, so the sandbox visitor wraps them with CheckToStringNode and the policy is consulted before PHP coerces the key to a string. The compiler also keeps an explicit (string) cast around the wrapped expression so PHP type errors on non-string keys are preserved.
As a side effect, any expression is now accepted as a dynamic mapping key (not only context variables); this is documented as a new feature on the 3.x branch.
Credits
Twig would like to thank El Kharoubi Iosif for reporting the issue and Fabien Potencier for providing the fix.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | twig/twig | all versions | 3.27.0composer require twig/twig:^3.27.0 |
Affected Products
twigsymfonyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for twig/twig, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update twig/twig to 3.27.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48806 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2026-48806 in your dependencies?
Find it across Packagist, including transitive dependencies.