Cookie value drops = (equal character, 0x3d)

[janigro]

Hi!

• Application version: 16.0.1
• Operating System (Platform and Version): macOS 11.4

Actual vs Expected Behavior
The server replied with a cookie in its response, and looked like this:

set-cookie: foo=bBRrE9bLezh+bRbQr7jBRd+4jfM7iCrsxe0s1fr4f3I=; Path=/; SameSite=Lax

however, the next request from the Advanced REST Client, dropped the trailing equal character, and the request header looked like this:

cookie: SameSite=Lax; foo=bBRrE9bLezh+bRbQr7jBRd+4jfM7iCrsxe0s1fr4f3I

when it should have looked like this:

cookie: SameSite=Lax; foo=bBRrE9bLezh+bRbQr7jBRd+4jfM7iCrsxe0s1fr4f3I=

Additional Information
Editing the cookie value from the cookie manager window to add an equal character at the end, before doing the request, works fine. But that only works once, because the client will drop the character again after every response.

According to page 8 in RFC6265, the 0x3d (=) character is permitted for the cookie value:

 cookie-value      = *cookie-octet / ( DQUOTE *cookie-octet DQUOTE )
 cookie-octet      = %x21 / %x23-2B / %x2D-3A / %x3C-5B / %x5D-7E
                       ; US-ASCII characters excluding CTLs,
                       ; whitespace DQUOTE, comma, semicolon,
                       ; and backslash

[Leon0402]

Ran into this issue today as well. Searched quite some time to find this issue!