CVE-2026-69183
Monkeytype: Rate-limit and anti-brute-force controls bypassable via spoofed HTTP headers (forgotPasswordEmail/verificationEmail mail bombing and badAuth bypass)
Description
Monkeytype is a minimalistic and customizable typing test. In 26.26.0 and earlier, the backend rate-limit key generator in backend/src/middlewares/rate-limit.ts uses client-controlled cf-connecting-ip and x-forwarded-for headers before the trust-proxy-derived req.ip value. An unauthenticated attacker can rotate either header to create a new bucket for each request, bypassing rootRateLimiter, badAuthRateLimiter, getKey(), and the getKeyWithUid() fallback used by public endpoints. This permits repeated POST /users/forgotPasswordEmail and verificationEmail requests, mail bombing registered users, consuming Firebase or SMTP quota, evading brute-force protection, and enabling resource exhaustion. Exploitability of cf-connecting-ip depends on deployment topology, but x-forwarded-for and direct-to-origin paths remain affected when those values are not overwritten by a trusted proxy. No fixed version is available as of this review.
INFO
Published Date :
Aug. 20, 2026, 4:16 p.m.
Last Modified :
Aug. 20, 2026, 4:16 p.m.
Remotely Exploit :
No
Source :
GitHub_M
Affected Products
The following products are affected by CVE-2026-69183
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Validate headers before trust-proxy-derived req.ip.
- Implement robust rate limiting checks.
- Monitor and log suspicious requests.
- Update to a patched version when available.
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CVE-2026-69183 vulnerability anywhere in the article.