CVE-2026-71380: httpd applies no timeout while receiving a request body, parking a worker on a stalled client
Missing Release of Resource after Effective Lifetime vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by sending valid request headers with a large Content-Length and then stalling before the body is complete.
httpdrequesthandler:handleinfo/2 cancels the request timeout as soon as a parse step succeeds, which includes the headers, and the clause that handles a decoder asking for more data re-arms the socket with {active, once} without setting any further timer. httpdrequest:wholebody/2 returns such a continuation whenever the bytes received are fewer than the announced Content-Length, so a well-formed request that stops mid-body leaves the worker waiting indefinitely. The periodic byte-rate check that would reclaim it is armed only when minimumbytespersecond is configured, which it is not by default. Repeating this across connections occupies every worker permitted by maxclients and denies service to legitimate clients at negligible bandwidth cost.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Erlang/OTP inets httpd (OTP application: inets)to a version that resolves this vulnerability.Fixed in 27.3.4.17 - Upgrade
Upgrade
Erlang/OTP inets httpd (OTP application: inets)to a version that resolves this vulnerability.Fixed in 28.5.0.6 - Upgrade
Upgrade
Erlang/OTP inets httpd (OTP application: inets)to a version that resolves this vulnerability.Fixed in 29.0.6 - Upgrade
Upgrade
Erlang/OTP inets (inets application)to a version that resolves this vulnerability.Fixed in 9.3.2.7 - Upgrade
Upgrade
Erlang/OTP inets (inets application)to a version that resolves this vulnerability.Fixed in 9.6.2.3 - Upgrade
Upgrade
Erlang/OTP inets (inets application)to a version that resolves this vulnerability.Fixed in 9.7.2 - Configuration
Configure minimum_bytes_per_second so the periodic byte-rate check that would reclaim stalled resources is armed (it is not by default).
inets httpd minimum_bytes_per_second = configured (not left at default) - Compensating control
Use a network-level mitigation to limit request body stalling (e.g., enforce upstream timeouts/limits for HTTP request bodies and per-connection rate/connection caps) so stalled clients cannot occupy all max_clients workers.
Event History
Frequently Asked Questions
Is the default httpd configuration affected?
Yes. The periodic byte-rate check that can reclaim stalled request workers is only enabled when minimum_bytes_per_second is configured, and it is not configured by default.
What does an attacker need to do to exhaust the service?
An unauthenticated remote attacker can send valid request headers declaring a large Content-Length, then stop sending the request body before it is complete. Each such connection can leave a worker waiting indefinitely.
How much service capacity can this consume?
Repeating the stalled requests across connections can occupy every worker allowed by max_clients. Once those workers are occupied, legitimate clients can be denied service at negligible attacker bandwidth cost.
What mitigation is available if upgrading cannot happen immediately?
Configure minimum_bytes_per_second so the periodic byte-rate check is armed and can reclaim stalled requests. The issue affects OTP 17.0 before 27.3.4.17, OTP 28.0 before 28.5.0.6, and OTP 29.0 before 29.0.6.