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HIGH

CVE-2020-7663

CVSS v3

7.5

HIGH

EPSS Score

4.6 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • websocket-extensionsRubyGemsall versions · fixed in 0.1.5

Vendor advisories

  • CVE-2020-7663 Red Hat Product Security1,251 products fixed · 2 known affected

    rubygem-websocket-extensions: ReDoS vulnerability in Sec-WebSocket-Extensions parser

    cfme-gemset as a component of CloudForms Management Engine 5 · cfme-gemset.src as a component of CloudForms Management Engine 5

  • RHSA-2020:4366 Red Hat Product Security1,251 products fixed

    Red Hat Security Advisory: Satellite 6.8 release

Full record on NVD

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.

Technical details

Published
2020-06-02

Frequently asked questions

What is CVE-2020-7663?

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.

Is CVE-2020-7663 actively exploited?

Active exploitation of CVE-2020-7663 has not been confirmed. Its EPSS score was 4.6% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-7663?

CVE-2020-7663 has a CVSS v3 base score of 7.5 (HIGH severity).

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