In PHP from 8.1.* before 8.1.32, from 8.2.* before 8.2.28, from 8.3.* before 8.3.19, from 8.4.* before 8.4.5, when receiving headers from HTTP server, the headers missing a colon (:) are treated as valid headers even though they are not. This may confuse applications into accepting invalid headers.
Exploitability
AV:NAC:HAT:PPR:NUI:NVulnerable System
VC:LVI:NVA:NSubsequent System
SC:NSI:NSA:N6.3/CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:NInput Validation