high8.2

CVE-2020-7663

Regular Expression Denial of Service in websocket-extensions (RubyGem)

Impact

### Impact The ReDoS flaw allows an attacker to exhaust the server's capacity to process incoming requests by sending a WebSocket handshake request containing a header of the following form: Sec-WebSocket-Extensions: a; b="\c\c\c\c\c\c\c\c\c\c ... That is, a header containing an unclosed string parameter value whose content is a repeating two-byte sequence of a backslash and some other character. The parser takes exponential time to reject this header as invalid, and this will block the processing of any other work on the same thread. Thus if you are running a single-threaded server, such a request can render your service completely unavailable. ### Patches Users should upgrade to version 0.1.5. ### Workarounds There are no known work-arounds other than disabling any public-facing WebSocket functionality you are operating. ### References - https://blog.jcoglan.com/2020/06/02/redos-vulnerability-in-websocket-extensions/

Affected packages

Ecosystem	Package	Affected	Fixed in
rubygems	`websocket-extensions`	< 0.1.5	0.1.5

Affected products

Vendor	Product	Affected versions
Websocket-Extensions Project	Websocket-Extensions	before 0.1.5
Debian	Debian Linux	Version 9.0
Canonical	Ubuntu Linux	Versions 16.04, 18.04, 20.04

Weakness classification

CWE-400