The urllib.parse.urlsplit() and urlparse() functions improperly validated bracketed hosts ([]), allowing hosts that weren't IPv6 or IPvFuture. This behavior was not conformant to RFC 3986 and potentially enabled SSRF if a URL is processed by more than one URL parser.
Exploitability
AV:NAC:HAT:PPR:NUI:NVulnerable System
VC:NVI:LVA:NSubsequent System
SC:NSI:LSA:N6.3/CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/AU:N