Security advisory
websocket-extensions ruby module prior to 0.1.5 allows Denial of Service (DoS) via Regex Backtracking. The extension parser may take quadratic time when parsing a header containing an unclosed string parameter value whose content is a repeating two-byte sequence of a backslash and some other character. This could be abused by an attacker to conduct Regex Denial Of Service (ReDoS) on a single-threaded server by providing a malicious payload with the Sec-WebSocket-Extensions header.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2020-7663
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 08:54 UTC · Revision 1
Source evidence
websocket-extensions ruby module prior to 0.1.5 allows Denial of Service (DoS) via Regex Backtracking. The extension parser may take quadratic time when parsing a header containing an unclosed string parameter value whose content is a repeating two-byte sequence of a backslash and some other character. This could be abused by an attacker to conduct Regex Denial Of Service (ReDoS) on a single-threaded server by providing a malicious payload with the Sec-WebSocket-Extensions header.
osv:CVE-2020-7663
Complete source record
{
"id": "1942c1b4a41e816248c62c7b3dcec60454e0bf6e51a9fa1469bfc745e1473a29",
"url": "https://osv.dev/vulnerability/CVE-2020-7663",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2020-7663",
"summary": "websocket-extensions ruby module prior to 0.1.5 allows Denial of Service (DoS) via Regex Backtracking. The extension parser may take quadratic time when parsing a header containing an unclosed string parameter value whose content is a repeating two-byte sequence of a backslash and some other character. This could be abused by an attacker to conduct Regex Denial Of Service (ReDoS) on a single-threaded server by providing a malicious payload with the Sec-WebSocket-Extensions header.",
"evidence": "osv:CVE-2020-7663",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2020-7663",
"aliases": [
"CVE-2020-7663",
"GHSA-g6wq-qcwm-j5g2",
"SNYK-RUBY-WEBSOCKETEXTENSIONS-570830"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/faye/websocket-extensions-ruby",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "aa156a439da681361ed6f53f1a8131892418838b"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"fixed": "aa156a439da681361ed6f53f1a8131892418838b"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"0.1.4",
"0.1.3",
"0.1.2",
"0.1.1",
"0.1.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-7663.json"
}
}
],
"modified": "2026-10-24T10:50:39.922345923Z",
"provider": "osv",
"references": [
"https://blog.jcoglan.com/2020/06/02/redos-vulnerability-in-websocket-extensions",
"https://github.com/faye/websocket-extensions-ruby/security/advisories/GHSA-g6wq-qcwm-j5g2",
"https://lists.debian.org/debian-lts-announce/2020/08/msg00031.html",
"https://usn.ubuntu.com/4502-1/",
"https://github.com/faye/websocket-extensions-ruby/commit/aa156a439da681361ed6f53f1a8131892418838b",
"https://snyk.io/vuln/SNYK-RUBY-WEBSOCKETEXTENSIONS-570830"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:a:websocket-extensions_project:websocket-extensions:*:*:*:*:*:ruby:*:*"
],
"vendor_product": "websocket-extensions_project:websocket-extensions",
"extracted_events": [
{
"range": [
{
"fixed": "0.1.5"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
"cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*",
"cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*",
"cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*"
],
"vendor_product": "canonical:ubuntu_linux",
"extracted_events": [
{
"range": [
{
"introduced": "16.04"
},
{
"last_affected": "16.04"
},
{
"introduced": "18.04"
},
{
"last_affected": "18.04"
},
{
"introduced": "20.04"
},
{
"last_affected": "20.04"
}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
"cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*"
],
"vendor_product": "debian:debian_linux",
"extracted_events": [
{
"range": [
{
"introduced": "9.0"
},
{
"last_affected": "9.0"
}
],
"source": "CPE_STRING"
}
]
},
{
"extracted_events": [
{
"range": [
{
"fixed": "0.1.5"
}
],
"source": "DESCRIPTION"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2020-7663",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 442435,
"published_at": "2020-06-02T19:15:12.467+00:00"
}