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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-32688 Detail

Description

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

Nist CVSS score does not match with CNA score
CNA:  EEF
CVSS-B 8.7 HIGH
Vector:  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

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://cna.erlef.org/cves/CVE-2026-32688.html EEF Third Party Advisory 
https://github.com/elixir-plug/plug_cowboy/commit/bfb34cb45eb354e56437f7023fb306de1bf9c19b EEF Patch 
https://github.com/elixir-plug/plug_cowboy/security/advisories/GHSA-q8x4-x7mp-5vg2 EEF Vendor Advisory 
https://osv.dev/vulnerability/EEF-CVE-2026-32688 EEF Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-770 Allocation of Resources Without Limits or Throttling EEF  

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Change History

4 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-32688
NVD Published Date:
04/27/2026
NVD Last Modified:
06/17/2026
Source:
EEF