Affected: Erlang OTP

The Erlang/OTP httpc HTTP client does not enforce a limit on the total size of response headers received from a server. The max_header_size option defaults to nolimit, and httpc_response:parse_headers/6 accumulates every header into a list before the length check runs (which only fires after the terminating CRLF CRLF is received).

A malicious or compromised HTTP server can send an arbitrarily large number of headers, or headers with very large values, causing the client process to allocate unbounded memory until the system runs out of memory or the BEAM VM crashes. A proof-of-concept server sending 100,000 headers of roughly 4000 bytes each caused the client VM to allocate over 13 GB of memory in under 30 seconds.

Any application using httpc:request/4,5 to connect to untrusted servers is affected. No authentication is required: any server the client connects to (including via a redirect or man-in-the-middle) can trigger the exhaustion.

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: Ubuntu:Pro:14.04:LTS: erlang, Ubuntu:Pro:16.04:LTS: erlang, Ubuntu:Pro:18.04:LTS: erlang, Ubuntu:Pro:20.04:LTS: erlang, Ubuntu:22.04:LTS: erlang, Ubuntu:24.04:LTS: erlang, Ubuntu:26.04:LTS: erlang

It was discovered that the Erlang Port Mapper Daemon did not properly handle slow connections. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-42792)

It was discovered that Erlang incorrectly handled certain external term format data, leading to heap corruption. An attacker could possibly use this issue to cause Erlang to crash, resulting in a denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-55737)

It was discovered that Erlang incorrectly handled invalid external term format data. An attacker could possibly use this issue to cause Erlang to crash, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-54890)

It was discovered that Erlang incorrectly handled certain packet lengths, leading to a buffer overflow. A remote attacker could possibly use this issue to cause Erlang to crash or execute arbitrary code. (CVE-2026-75538)

It was discovered that the Erlang Megaco flex scanner incorrectly handled certain input, leading to a buffer overflow. A remote attacker could possibly use this issue to cause Erlang to crash or execute arbitrary code. (CVE-2026-59250)

It was discovered that Erlang TLS clients incorrectly accepted cipher suites that they had not offered. A remote attacker could possibly use this issue to intercept and modify TLS communications. (CVE-2026-55953)

It was discovered that Erlang incorrectly handled certain certificate chains. A remote att…