CVE-2026-32688: Atom table exhaustion via HTTP/2 :scheme pseudo-header in plug_cowboy
elixir-plug · plug_cowboy
Fixed in 2.8.1 · Affected: elixir-plug plug_cowboy before 2.8.1 · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 46% of scored CVEs
DescriptionCVE.org
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 products2
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- elixir-plug · plug_cowboyfrom 2.0.0 before 2.8.1
- elixir-plug · plug_cowboyVersions not stated
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- elixir-plug
- Published
- April 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-32688 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.