CVE Catalog

CVE-2026-32688

High
Published: Translated: NVD NIST

Summary

A vulnerability in elixir-plug plug_cowboy allows unauthenticated remote denial of service via atom table exhaustion. An attacker can send unique :scheme header values in HTTP/2 requests, leading to the Erlang VM aborting.

Risk Assessment

The organization may experience service downtime, which can lead to loss of customer trust and potential financial losses. Exhausting the atom table can cause the entire node to crash.

Recommendation

It is recommended to update plug_cowboy to version 2.8.1 or later to mitigate the risk associated with this vulnerability. Additionally, implementing restrictions on accepted header values in HTTP/2 requests is advisable.

Related vulnerabilities

Original NVD description (English source)

Allocation of Resources Without Limits or Throttling vulnerability in elixir-plug plug_cowboy allows unauthenticated remote denial of service via atom table exhaustion. Plug.Cowboy.Conn.conn/1 in lib/plug/cowboy/conn.ex calls String.to_atom/1 on the value returned by :cowboy_req.scheme/1. For HTTP/2 connections, cowlib passes the client-supplied :scheme pseudo-header value through verbatim without validation. Each unique value permanently allocates a new entry in the BEAM atom table. Since atoms are never garbage-collected and the atom table has a fixed limit (default 1,048,576), an unauthenticated attacker can exhaust the table by sending HTTP/2 requests with unique :scheme values, causing the Erlang VM to abort with system_limit and taking down the entire node. This vulnerability does not affect HTTP/1.1, where cowboy derives the scheme from the listener type rather than from a client-supplied header. This issue affects plug_cowboy: from 2.0.0 before 2.8.1.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS