CVE-2026-33621 PinchTab: Unapplied Rate Limiting Middleware Allows Unbounded Brute-Force of API Token
Missing rate limiting allows unbounded brute-force attacks against API tokens, potentially leading to service exhaustion or unauthorized access if tokens are weak.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33621?
CVE-2026-33621 is a medium-severity denial of service vulnerability in pinchtab, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
PinchTab is a standalone HTTP server that gives AI agents direct control over a Chrome browser. PinchTab `v0.7.7` through `v0.8.4` contain incomplete request-throttling protections for auth-checkable endpoints. In `v0.7.7` through `v0.8.3`, a fully implemented `RateLimitMiddleware` existed in `internal/handlers/middleware.go` but was not inserted into the production HTTP handler chain, so requests were not subject to the intended per-IP throttle. In the same pre-`v0.8.4` range, the original limiter also keyed clients using `X-Forwarded-For`, which would have allowed client-controlled header spoofing if the middleware had been enabled. `v0.8.4` addressed those two issues by wiring the limiter into the live handler chain and switching the key to the immediate peer IP, but it still exempted `/health` and `/metrics` from rate limiting even though `/health` remained an auth-checkable endpoint when a token was configured. This issue weakens defense in depth for deployments where an attacker can reach the API, especially if a weak human-chosen token is used. It is not a direct authentication bypass or token disclosure issue by itself. PinchTab is documented as local-first by default and uses `127.0.0.1` plus a generated random token in the recommended setup. PinchTab's default deployment model is a local-first, user-controlled environment between the user and their agents; wider exposure is an intentional operator choice. This lowers practical risk in the default configuration, even though it does not by itself change the intrinsic base characteristics of the bug. This was fully addressed in `v0.8.5` by applying `RateLimitMiddleware` in the production handler chain, deriving the client address from the immediate peer IP instead of trusting forwarded headers by default, and removing the `/health` and `/metrics` exemption so auth-checkable endpoints are throttled as well.
Which versions are affected by CVE-2026-33621?
3 open source packages ship an affected version, including github.com/pinchtab/pinchtab. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/pinchtab/pinchtab Go | From 0.7.7 | 0.8.5 |
github.com/pinchtab/pinchtab Go | From 0.7.7 | 0.8.5 |
github.com/pinchtab/pinchtab Go | From 0.7.7 | 0.8.5 |
Products include Pinchtab Pinchtab.
How do I fix CVE-2026-33621?
Upgrade github.com/pinchtab/pinchtab to 0.8.5 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-33621 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33621 exists.
Other vulnerabilities in pinchtab
- CVE-2026-30834 PinchTab: SSRF with Full Response Exfiltration via Download Handler
- CVE-2026-33623 PinchTab: OS Command Injection via Profile Name in Windows Cleanup Routine Enables Arbitrary Command Execution
- CVE-2026-33622 A PinchTab Security Policy Bypass in /wait Allows Arbitrary JavaScript Execution
- CVE-2026-33081 PinchTab has Blind SSRF via browser-side redirect bypass in /download URL validation
- CVE-2026-33620 PinchTab: API Bearer Token Exposed in URL Query Parameter via Server Logs and Intermediary Systems
Sources
Also known as GHSA-j65m-hv65-r264, GO-2026-4821.