CVE-2026-32688

The record

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.

Affected packages

Related vulnerabilities

• CVE-2026-114731 Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by an uncontrolled… CWE-770
• CVE-2026-96377 Allocation of Resources Without Limits or Throttling vulnerability in Drupal Combined… CWE-770
• CVE-2026-96365 Allocation of Resources Without Limits or Throttling vulnerability in Drupal Webform… CWE-770
• CVE-2026-114723 Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 allows the ImageMagick resource… CWE-770
• CVE-2026-113811 Algorithm::UrataniTakeda versions from 0.1.5 before 0.1.7 for Perl allow memory… CWE-770
• CVE-2026-113795 pypdf is a free and open-source pure-python PDF library. CWE-770
• CVE-2026-112400 Pillow is a Python imaging library. CWE-770
• CVE-2026-111064 AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. CWE-770