CVE-2026-71562: Erlang OTP

Medium severity, CVSS 6.3. EPSS: 0.6% chance of exploitation in the next 30 days.

Improper Validation of Specified Quantity in Input vulnerability in Erlang/OTP inets httpc allows a malicious or compromised HTTP server to degrade availability by returning a numeric header whose value is a very long run of digits. httpc_handler.erl converts the server-supplied Content-Length with list_to_integer/1 before comparing it against max_body_size, so the size check cannot protect the conversion, and the option defaults to nolimit in any case. The same unbounded conversion appears in httpc_response:format_response/1 for Content-Length and in httpc_response:get_ms_from_retry_after/1 for Retry-After, which is guarded only by a check that the first character is a digit. A value of up to roughly 1.26 million digits converts successfully and costs the requesting process hundreds of milliseconds of arbitrary-precision arithmetic per response. The conversion function is documented to accept integers of any size, so bounding the input is the caller's responsibility. 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 products

• Erlang OTP: from 17.0, before 27.3.4.17 (fixed in 27.3.4.17); from 28.0, before 28.5.0.6 (fixed in 28.5.0.6); from 29.0, before 29.0.6 (fixed in 29.0.6); from 5.10, before 9.3.2.7 (fixed in 9.3.2.7); from 9.4, before 9.6.2.3 (fixed in 9.6.2.3); from 9.7, before 9.7.2 (fixed in 9.7.2)

Published 2026-09-01. Last modified 2026-09-08.