[exim-dev] [Bug 3063] "SMTP Smuggling" attack

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Lähettäjä: Exim Bugzilla
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Vastaanottaja: exim-dev
Vanhat otsikot: [exim-dev] [Bug 3063] New: Partially vulnerable to "SMTP Smuggling" if pipelining is enabled
Aihe: [exim-dev] [Bug 3063] "SMTP Smuggling" attack
https://bugs.exim.org/show_bug.cgi?id=3063

--- Comment #13 from Simon Arlott <bugzilla.exim.simon@???> ---
(In reply to Simon Arlott from comment #7)
> > Dec 2023: getting a site to send a body including an "LF . LF" sequence
> > followed by SMTP commands is a possible "smtp smuggling" attack. If
> > the first (header) line for the message has a proper CRLF then enforce
> > that for the body: convert bare LF to a space.
>
> I expect that converting <LF> to a space is going to lead to further
> security or interoperability problems because it will mean Exim will merge
> two lines in a <CRLF>-based message if there's an <LF> in the middle of
> them, potentially changing the meaning of the message by merging two or more
> header lines together or merging the body with the headers.
>
> Can't it just accept the message as-is, using dot duplication if the entire
> line is "."?


Jeremy, you've still not explained why Exim is now changing message content
like this. Postfix and Sendmail don't do it.

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