vulnerability / NVI-00005111 / Revision 4
Twig: Sandbox: multiple `__toString()` policy bypasses via unguarded string coercion points
GitHub lists this reviewed advisory for twig/twig. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
6.5 MEDIUM (3.1)
nvd@nist.gov severity; no combined Null risk score.
7.1 HIGH (4.0)
security-advisories@github.com severity; no combined Null risk score.
0.402%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.34424. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
twig/twig
source listed<= 3.25.0
### Description `SandboxNodeVisitor` enforces `SecurityPolicy::checkMethodAllowed()` for implicit `__toString()` calls by wrapping selected AST nodes in `CheckToStringNode`. The set of wrapped nodes is incomplete, and several Twig language constructs still trigger PHP string coercion on a `Stringable` operand without first consulting the policy. A sandboxed template author can therefore invoke `__toString()` on any object reachable in the render context, even when `__toString` on its class is not allowlisted. Confirmed bypass vectors: - Conditional expressions (`a ? b : c`, `a ?: b`, `a ?? b`) used as the input of a string-coercing filter or as a filter/function argument. - The `matches` operator and the loose comparison operators (`==`, `!=`, ``, `=`, ``), which coerce a `Stringable` operand to string and can be used as an oracle to recover the value byte by byte (no tag, filter or function needs to be allowlisted). - Twig tests in general (which were never policy-gated), in particular `is empty` which casts a `Stringable` value via `(string) $value` in `CoreExtension::testEmpty()`. - Null-coalesce expressions nested in concatenation, and the direct output of al
twig/twig
source listedECOSYSTEM: introduced 0; fixed 3.26.0
### Description `SandboxNodeVisitor` enforces `SecurityPolicy::checkMethodAllowed()` for implicit `__toString()` calls by wrapping selected AST nodes in `CheckToStringNode`. The set of wrapped nodes is incomplete, and several Twig language constructs still trigger PHP string coercion on a `Stringable` operand without first consulting the policy. A sandboxed template author can therefore invoke `__toString()` on any object reachable in the render context, even when `__toString` on its class is not allowlisted. Confirmed bypass vectors: - Conditional expressions (`a ? b : c`, `a ?: b`, `a ?? b`) used as the input of a string-coercing filter or as a filter/function argument. - The `matches` operator and the loose comparison operators (`==`, `!=`, ``, `=`, ``), which coerce a `Stringable` operand to string and can be used as an oracle to recover the value byte by byte (no tag, filter or function needs to be allowlisted). - Twig tests in general (which were never policy-gated), in particular `is empty` which casts a `Stringable` value via `(string) $value` in `CoreExtension::testEmpty()`. - Null-coalesce expressions nested in concatenation, and the direct output of al
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
- vendor patch
The original advisory lists fixed boundaries 3.26.0 for twig/twig. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-pr2w-4gpj-cpq4 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- GHSA-pr2w-4gpj-cpq4 ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2026-47732 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
- CVE-2026-47732 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 4 ·
Source facts changed; compare the preserved prior revision.
- Revision 3 ·
Source facts changed; compare the preserved prior revision.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.