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 http request module parses HTTP response obtained from a server, folded headers are parsed incorrectly, which may lead to misinterpreting the response and using incorrect headers, MIME types, etc.

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 requesting a HTTP resource using the DOM or SimpleXML extensions, the wrong content-type header is used to determine the charset when the requested resource performs a redirect. This may cause the resulting document to be parsed incorrectly or bypass validations.

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.

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 user-supplied headers are sent, the insufficient validation of the end-of-line characters may prevent certain headers from being sent or lead to certain headers be misinterpreted.

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 parsing HTTP redirect in the response to an HTTP request, there is currently limit on the location value size caused by limited size of the location buffer to 1024. However as per RFC9110, the limit is recommended to be 8000. This may lead to incorrect URL truncation and redirecting to a wrong location.