EEF-CVE-2026-32688
- Source
- https://cna.erlef.org/osv/EEF-CVE-2026-32688.html
- Import Source
- https://cna.erlef.org/osv/EEF-CVE-2026-32688.json
- JSON Data
- https://api.osv.dev/v1/vulns/EEF-CVE-2026-32688
- Aliases
-
- CVE-2026-32688
- GHSA-q8x4-x7mp-5vg2
- Published
- 2026-04-27T13:45:35.160Z
- Modified
- 2026-04-28T04:25:01.084Z
- Severity
-
- 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CVSS Calculator
- Summary
- Atom table exhaustion via HTTP/2 :scheme pseudo-header in plug_cowboy
- Details
-
Summary
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.toatom/1 on the value returned by :cowboyreq.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.
Workaround
Disable HTTP/2 on the Plug.Cowboy.https/3 listener by passing protocol_options: %{protocols: [:http]} in the cowboy options. This restricts the listener to HTTP/1.1, where the scheme is derived from the listener type and is not attacker-controlled.
- Database specific
{ "cpe_ids": [ "cpe:2.3:a:elixir-plug:plug_cowboy:*:*:*:*:*:*:*:*" ], "cwe_ids": [ "CWE-770" ], "capec_ids": [ "CAPEC-125" ] }- References
- Credits
-
-
- Peter Ullrich - FINDER
-
Affected packages
Hex / plug_cowboy
Package
- Name
- plug_cowboy
- Purl
- pkg:hex/plug_cowboy