Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows an…

Why it is Yellow

• CVSS 8.2 high
• Remotely exploitable without logging in

References

• https://cna.erlef.org/cves/CVE-2026-115701.html
• https://github.com/ninenines/cowboy/commit/3a630c07e1521abf63a1b9ea080509aa1337b60d
• https://github.com/ninenines/cowboy/commit/faf5594fbf74530ace90b0c46c936bdc2cf82081
• https://osv.dev/vulnerability/EEF-CVE-2026-115701

Original description

Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows an unauthenticated remote attacker to exhaust connection process memory over HTTP/1.1. Once a request has been received in full and its handler is still running, cowboy_http:parse/2 in src/cowboy_http.erl appends every further byte that arrives on the keep-alive connection to the connection buffer and returns to the receive loop without parsing it. The socket stays in active mode and no limit applies to this buffer: max_request_line_length, max_headers and the other parser limits only take effect once the handler returns and parsing resumes, and the only timer in this state is idle_timeout (default 60 seconds), which is reset on every received chunk. A client can therefore send an arbitrary amount of data on one connection for as long as the handler runs, and a few connections to an endpoint that holds requests open can drive the Erlang VM into out-of-memory conditions. This issue affects cowboy: from 2.18.0 onward.