{
"id": "GHSA-6983-jfq8-485w",
"aliases": [
"CVE-2026-56811"
],
"details": "### Summary\n\nPhoenix transports do not limit the number of channels in a given connection, making it easy to spawn hundreds of thousands of processes over a single connection, and, eventually reaching the max processes VM limit. The solution is to limit the number of channels per transport, so an attacker needs to start new HTTP/WebSocket connections, allowing third-party services to apply rate limits and intervene more easily.\n\n### Impact\n\nAn unauthenticated remote attacker can cause a denial of service against any Phoenix app that exposes LongPoll/WebSocket transports.",
"summary": "Phoenix: Unbounded channel joins per transport enables DoS over few connections",
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0.11.0"
},
{
"fixed": "1.5.15"
}
]
}
],
"package": {
"name": "phoenix",
"ecosystem": "Hex"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "1.6.0-rc.0"
},
{
"fixed": "1.6.17"
}
]
}
],
"package": {
"name": "phoenix",
"ecosystem": "Hex"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "1.7.0-rc.0"
},
{
"fixed": "1.7.24"
}
]
}
],
"package": {
"name": "phoenix",
"ecosystem": "Hex"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "1.8.0-rc.0"
},
{
"fixed": "1.8.9"
}
]
}
],
"package": {
"name": "phoenix",
"ecosystem": "Hex"
}
}
],
"modified": "2026-09-03T20:33:03Z",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "CVSS_V4",
"score": "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"
}
],
"published": "2026-09-03T20:33:03Z",
"references": [
{
"url": "https://github.com/phoenixframework/phoenix/security/advisories/GHSA-6983-jfq8-485w",
"type": "WEB"
},
{
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-56811",
"type": "ADVISORY"
},
{
"url": "https://github.com/phoenixframework/phoenix/commit/16e295d2fccab185d1292322e2bee5d46c725c8a",
"type": "WEB"
},
{
"url": "https://github.com/phoenixframework/phoenix/commit/a612100cd8a4279091abc1a2ef8fb98a6d01c0a1",
"type": "WEB"
},
{
"url": "https://github.com/phoenixframework/phoenix/commit/c498ba8cf49f6accbbd0c643a5340b58db891218",
"type": "WEB"
},
{
"url": "https://github.com/phoenixframework/phoenix/commit/d19ca0a8d9f82c130b7ed339b9f033433e2dea5e",
"type": "WEB"
},
{
"url": "https://cna.erlef.org/cves/CVE-2026-56811.html",
"type": "WEB"
},
{
"url": "https://github.com/phoenixframework/phoenix",
"type": "PACKAGE"
},
{
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-56811",
"type": "WEB"
}
],
"schema_version": "1.4.0",
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"severity": "HIGH",
"github_reviewed": true,
"nvd_published_at": "2026-07-07T16:16:40Z",
"github_reviewed_at": "2026-09-03T20:33:03Z"
}
}