CVE-2026-32688

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Source
https://cve.org/CVERecord?id=CVE-2026-32688
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-32688.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-32688
Aliases
Published
2026-04-27T13:45:35.160Z
Modified
2026-07-08T08:12:58.604425854Z
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

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.

Database specific 
{
    "unresolved_ranges": [
        {
            "source": "AFFECTED_FIELD",
            "extracted_events": [
                {
                    "introduced": "12ecfd024bb179d48b018fecf074e43fe6a19c83"
                },
                {
                    "fixed": "bfb34cb45eb354e56437f7023fb306de1bf9c19b"
                }
            ]
        }
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32688.json",
    "cwe_ids": [
        "CWE-770"
    ],
    "cna_assigner": "EEF"
}
References

Affected packages

Git / github.com/elixir-plug/plug_cowboy

Affected ranges

Type
GIT
Repo
https://github.com/elixir-plug/plug_cowboy
Events
Introduced
8d60f2912743834b48544e6fd1f01f832d660cb1
Fixed
fd0841f4ef974b95a5050a2b5959585c56fb3776
Fixed
bfb34cb45eb354e56437f7023fb306de1bf9c19b
Database specific 
{
    "source": [
        "CPE_RANGE",
        "REFERENCES"
    ],
    "cpe": "cpe:2.3:a:elixir-plug:plug.cowboy:*:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "2.0.0"
        },
        {
            "fixed": "2.8.1"
        }
    ]
}

Affected versions

v2.*
v2.0.0
v2.0.1
v2.0.2
v2.1.0
v2.1.1
v2.1.2
v2.2.0
v2.2.1
v2.2.2
v2.3.0
v2.4.0
v2.5.0
v2.5.1
v2.5.2
v2.6.0
v2.6.1
v2.6.2
v2.7.0
v2.7.1
v2.7.2
v2.7.3
v2.7.4
v2.7.5
v2.8.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-32688.json"