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CVE-2026-48806 critical CVSS 9.1

Vulnerability in twig/twig (CVE-2026-48806)

Summary

Vulnerability in twig/twig (CVE-2026-48806). Confidential information can be exposed externally. Exploitable via CheckToStringNode. Mitigation: upgrade to 3.27.0 or later.

Original description

The description as published by the source.

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 expressio…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-48806 has been found in twig/twig.
Attackers can target a specific entry point like CheckToStringNode over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 9.1/10.
What to do: upgrade twig/twig to 3.27.0 or later.
If unsure, ask your IT team or search "twig/twig CVE-2026-48806" on the vendor's site.

CVE-2026-48806 (twig/twig) — CWE-693 / CVSS v3 9.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: CheckToStringNode / CoercesChildrenToStringInterface / ArrayExpression / Stringable
Patched: 3.27.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-693) exists in twig/twig. Attackers reach the vulnerable code path via CheckToStringNode without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of twig/twig. Attack surface: CheckToStringNode / CoercesChildrenToStringInterface / ArrayExpression / Stringable.

🔥 Severity

Severity: Critical (CVSS 9.1/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 3.27.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'twig/twig' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'twig/twig' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で twig/twig を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade twig/twig to 3.27.0

    ステージング環境で 3.27.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

composer twig/twig
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.27.0"}]}]
Packagist twig/twig
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.27.0"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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