CVE-2026-71562
MediumCVSS 6.3Summary
The httpc module in Erlang/OTP inets has an improper validation of specified quantity vulnerability. A malicious or compromised HTTP server can degrade availability by returning a numeric header with a very long run of digits, causing expensive integer conversion.
Risk Assessment
An attacker can cause CPU exhaustion in the client process, leading to performance degradation and potential denial of service.
Recommendation
Update OTP to version 27.3.4.17, 28.5.0.6, or 29.0.6 (or later) and consider limiting header sizes in client configuration.
Other vulnerabilities in Erlang/OTP inets
See all- CVE-2026-74994Medium
The mod_auth module in OTP's inets httpd server, when configured with dets or mnesia authentication backends and multiple directory configuration blocks, collapses all directory blocks into a single shared user/group namespace. A user added to one protected directory is accepted as valid for all other protected directories on the same server instance.
- CVE-2026-73270High
A vulnerability in the inets HTTP server in Erlang/OTP allows a remote unauthenticated attacker to read files in a mod_auth protected directory by requesting them with different casing, on case-insensitive filesystems. The path check does not use the caseless option, allowing authentication bypass.
- CVE-2026-71380High
A vulnerability in the inets HTTP server in Erlang/OTP allows a remote unauthenticated attacker to cause denial of service by sending valid headers with a large Content-Length and then stalling. The server cancels the request timeout after header parsing and does not re-arm it, leaving workers waiting indefinitely.
- CVE-2026-70399High
A vulnerability in the inets HTTP server in Erlang/OTP allows a remote unauthenticated attacker to cause denial of service by opening and holding many connections. The max_clients option is not set by default, allowing unlimited simultaneous connections, leading to resource exhaustion.
- CVE-2026-66835High
A vulnerability in the inets HTTP server in Erlang/OTP allows a remote unauthenticated attacker to read files in a mod_auth protected directory by prefixing the request path with an extra slash. URI normalization does not collapse double slashes, causing the path check to miss the protected directory.
- CVE-2026-66357High
The inets HTTP server in Erlang/OTP does not implement obs-fold (header continuation lines), which may lead to HTTP request smuggling vulnerabilities. Every CRLF followed by a non-CRLF starts a new header, which can be exploited by an attacker.
Original NVD description (English source)
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.