{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-32688",
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "state": "PUBLISHED",
        "assignerShortName": "EEF",
        "dateReserved": "2026-03-13T09:12:14.475Z",
        "datePublished": "2026-04-27T13:45:35.160Z",
        "dateUpdated": "2026-04-29T17:08:07.227Z"
    },
    "containers": {
        "cna": {
            "affected": [
                {
                    "collectionURL": "https://repo.hex.pm",
                    "cpes": [
                        "cpe:2.3:a:elixir-plug:plug_cowboy:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "'Elixir.Plug.Cowboy.Conn'"
                    ],
                    "packageName": "plug_cowboy",
                    "packageURL": "pkg:hex/plug_cowboy",
                    "product": "plug_cowboy",
                    "programFiles": [
                        "lib/plug/cowboy/conn.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.Plug.Cowboy.Conn':conn/1"
                        }
                    ],
                    "repo": "https://github.com/elixir-plug/plug_cowboy",
                    "vendor": "elixir-plug",
                    "versions": [
                        {
                            "lessThan": "2.8.1",
                            "status": "affected",
                            "version": "2.0.0",
                            "versionType": "semver"
                        }
                    ]
                },
                {
                    "collectionURL": "https://github.com",
                    "cpes": [
                        "cpe:2.3:a:elixir-plug:plug_cowboy:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "'Elixir.Plug.Cowboy.Conn'"
                    ],
                    "packageName": "elixir-plug/plug_cowboy",
                    "packageURL": "pkg:github/elixir-plug/plug_cowboy",
                    "product": "plug_cowboy",
                    "programFiles": [
                        "lib/plug/cowboy/conn.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.Plug.Cowboy.Conn':conn/1"
                        }
                    ],
                    "repo": "https://github.com/elixir-plug/plug_cowboy",
                    "vendor": "elixir-plug",
                    "versions": [
                        {
                            "lessThan": "bfb34cb45eb354e56437f7023fb306de1bf9c19b",
                            "status": "affected",
                            "version": "12ecfd024bb179d48b018fecf074e43fe6a19c83",
                            "versionType": "git"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "cpeMatch": [
                                {
                                    "criteria": "cpe:2.3:a:elixir-plug:plug_cowboy:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "2.8.1",
                                    "versionStartIncluding": "2.0.0",
                                    "vulnerable": true
                                }
                            ],
                            "negate": false,
                            "operator": "OR"
                        }
                    ],
                    "operator": "AND"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Peter Ullrich"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "Allocation of Resources Without Limits or Throttling vulnerability in elixir-plug plug_cowboy allows unauthenticated remote denial of service via atom table exhaustion.<p><tt>Plug.Cowboy.Conn.conn/1</tt> in <tt>lib/plug/cowboy/conn.ex</tt> calls <tt>String.to_atom/1</tt> on the value returned by <tt>:cowboy_req.scheme/1</tt>. For HTTP/2 connections, cowlib passes the client-supplied <tt>:scheme</tt> 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 <tt>:scheme</tt> values, causing the Erlang VM to abort with <tt>system_limit</tt> and taking down the entire node.</p><p>This vulnerability does not affect HTTP/1.1, where cowboy derives the scheme from the listener type rather than from a client-supplied header.</p><p>This issue affects plug_cowboy: from 2.0.0 before 2.8.1.</p>"
                        }
                    ],
                    "value": "Allocation of Resources Without Limits or Throttling vulnerability in elixir-plug plug_cowboy allows unauthenticated remote denial of service via atom table exhaustion.\n\nPlug.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.\n\nThis vulnerability does not affect HTTP/1.1, where cowboy derives the scheme from the listener type rather than from a client-supplied header.\n\nThis issue affects plug_cowboy: from 2.0.0 before 2.8.1."
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-125",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-125 Flooding"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "attackVector": "NETWORK",
                        "baseScore": 8.7,
                        "baseSeverity": "HIGH",
                        "privilegesRequired": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "userInteraction": "NONE",
                        "vectorString": "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",
                        "version": "4.0",
                        "vulnAvailabilityImpact": "HIGH",
                        "vulnConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE"
                    },
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ]
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-770",
                            "description": "CWE-770 Allocation of Resources Without Limits or Throttling",
                            "lang": "en",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
                "shortName": "EEF",
                "dateUpdated": "2026-04-29T17:08:07.227Z"
            },
            "references": [
                {
                    "tags": [
                        "vendor-advisory",
                        "related"
                    ],
                    "url": "https://github.com/elixir-plug/plug_cowboy/security/advisories/GHSA-q8x4-x7mp-5vg2"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://cna.erlef.org/cves/CVE-2026-32688.html"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://osv.dev/vulnerability/EEF-CVE-2026-32688"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/elixir-plug/plug_cowboy/commit/bfb34cb45eb354e56437f7023fb306de1bf9c19b"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "title": "Atom table exhaustion via HTTP/2 :scheme pseudo-header in plug_cowboy",
            "workarounds": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "Disable HTTP/2 on the <tt>Plug.Cowboy.https/3</tt> listener by passing <tt>protocol_options: %{protocols: [:http]}</tt> 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."
                        }
                    ],
                    "value": "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."
                }
            ],
            "x_generator": {
                "engine": "cvelib 1.8.0"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-04-27T19:04:33.154446Z",
                                "id": "CVE-2026-32688",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "yes"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-04-27T20:11:22.651Z"
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    }
}