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2 vulnerabilities found for plug_cowboy by elixir-plug
CVE-2026-32688 (GCVE-0-2026-32688)
Vulnerability from nvd – Published: 2026-04-27 13:45 – Updated: 2026-04-29 17:08
VLAI
Title
Atom table exhaustion via HTTP/2 :scheme pseudo-header in plug_cowboy
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.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.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/elixir-plug/plug_cowboy/securi… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-32688.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-32688 | related |
| https://github.com/elixir-plug/plug_cowboy/commit… | patch |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| elixir-plug | plug_cowboy |
Affected:
2.0.0 , < 2.8.1
(semver)
cpe:2.3:a:elixir-plug:plug_cowboy:*:*:*:*:*:*:*:* |
|
| elixir-plug | plug_cowboy |
Affected:
12ecfd024bb179d48b018fecf074e43fe6a19c83 , < bfb34cb45eb354e56437f7023fb306de1bf9c19b
(git)
cpe:2.3:a:elixir-plug:plug_cowboy:*:*:*:*:*:*:*:* |
Credits
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CVE-2026-32688 (GCVE-0-2026-32688)
Vulnerability from cvelistv5 – Published: 2026-04-27 13:45 – Updated: 2026-04-29 17:08
VLAI
Title
Atom table exhaustion via HTTP/2 :scheme pseudo-header in plug_cowboy
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.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.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/elixir-plug/plug_cowboy/securi… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-32688.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-32688 | related |
| https://github.com/elixir-plug/plug_cowboy/commit… | patch |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| elixir-plug | plug_cowboy |
Affected:
2.0.0 , < 2.8.1
(semver)
cpe:2.3:a:elixir-plug:plug_cowboy:*:*:*:*:*:*:*:* |
|
| elixir-plug | plug_cowboy |
Affected:
12ecfd024bb179d48b018fecf074e43fe6a19c83 , < bfb34cb45eb354e56437f7023fb306de1bf9c19b
(git)
cpe:2.3:a:elixir-plug:plug_cowboy:*:*:*:*:*:*:*:* |
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