CVE-2026-33622: A PinchTab Security Policy Bypass in /wait Allows Arbitrary JavaScript Execution

Vulnerability summary

CVE-2026-33622 is a high (CVSS 8.8) Improper Control of Generation of Code vulnerability in pinchtab. EPSS estimates a 0.53% chance of exploitation in the next 30 days, higher than 45% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 26-03-2026
   PublishedVulnerability first disclosed.
2. 27-03-2026
   Last modifiedVulnerability information updated.

Description

PinchTab is a standalone HTTP server that gives AI agents direct control over a Chrome browser. PinchTab `v0.8.3` through `v0.8.5` allow arbitrary JavaScript execution through `POST /wait` and `POST /tabs/{id}/wait` when the request uses `fn` mode, even if `security.allowEvaluate` is disabled. `POST /evaluate` correctly enforces the `security.allowEvaluate` guard, which is disabled by default. However, in the affected releases, `POST /wait` accepted a user-controlled `fn` expression, embedded it directly into executable JavaScript, and evaluated it in the browser context without checking the same policy. This is a security-policy bypass rather than a separate authentication bypass. Exploitation still requires authenticated API access, but a caller with the server token can execute arbitrary JavaScript in a tab context even when the operator explicitly disabled JavaScript evaluation. The current worktree fixes this by applying the same policy boundary to `fn` mode in `/wait` that already exists on `/evaluate`, while preserving the non-code wait modes. As of time of publication, a patched version is not yet available.

• CWE-94Improper Control of Generation of CodeThe product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
• CWE-284Improper Access ControlThe product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
• CWE-693Protection Mechanism FailureThe product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.