CVE-2020-7663websocket-extensions ruby module prior to 0.1.5 allows Denial of Service (DoS) via Regex Backtracking. The extension parser may take…
- 7.5HighCVSS base score
- 4.6%Exploitation in 30 daysEPSS · top 8.2% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By snyk
- 4 months later
· 4 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 4.6% · top 8.2% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
websocket-extensions (ruby)
- affected All versions prior to 0.1.5
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- RubyGemswebsocket-extensionsGHSA-g6wq-qcwm-j5g2 (opens in a new tab)
References
References6
- https://github.com/faye/websocket-extensions-ruby/security/advisories/GHSA-g6wq-qcwm-j5g2 (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/faye/websocket-extensions-ruby/commit/aa156a439da681361ed6f53f1a8131892418838b (opens in a new tab)x_refsource_MISCx_transferred
- https://blog.jcoglan.com/2020/06/02/redos-vulnerability-in-websocket-extensions (opens in a new tab)x_refsource_MISCx_transferred
- https://snyk.io/vuln/SNYK-RUBY-WEBSOCKETEXTENSIONS-570830 (opens in a new tab)x_refsource_MISCx_transferred
- [debian-lts-announce] 20200819 [SECURITY] [DLA 2334-1] ruby-websocket-extensions security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- USN-4502-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2020-0487 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-g6wq-qcwm-j5g2 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2020-7663)Record last updated .