CVE-2026-33622CWE-284CWE-693CWE-94

A PinchTab Security Policy Bypass in /wait Allows Arbitrary JavaScript Execution

Medium · published March 26, 2026

CVSS v4.0
6.1
EPSS
1%
Percentile
55.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
6.1 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:N/SC:H/SI:N/SA:N
EPSS
0.00788 · 55.7th percentile
Weaknesses
CWE-284 · Improper Access Control; CWE-693 · Protection Mechanism Failure; CWE-94 · Improper Control of Generation of Code ('Code Injection')
Published
2026-03-26T20:44Z
EPSS history
Timeline
  • 26 MAR 20:44Z
    A PinchTab Security Policy Bypass in /wait Allows Arbitrary JavaScript Execution
    cvelistv5