Alberto Bertogli 61792e3bb4 Reject invalid characters in domains ...

Domains in addresses had very lax validation, which allowed them to
include characters like "/".

That could be exploited to trigger a daemon panic: a MAIL FROM
"x@evil/foo" could be accepted and, on failed delivery, a DSN queued.
Attempting to deliver the DSN would cause an MTA-STS cache lookup, which
would panic because the domain includes a "/" and crash the server.
Because the DSN would be queued, the server would crash again on
restarts, and only self-recover after give_up_send_after (20h by
default).

To fix this, we now explicitly validate the domain when normalizing it,
make MTA-STS cache not panic on invalid domains, and also make the SMTP
courier fail permanently on invalid domains.

Thanks to John JEAN <john@wargan.com> for finding and reporting this
problem. The detailed report can be found in
https://johnjean.io/advisories/chasquid-unauthenticated-remote-dos/.

2026-10-09 00:00:12 +01:00

..

testdata/fuzz

test: Update fuzz tests to use the built-in infrastructure

2023-02-05 12:30:25 +00:00

normalize_test.go

Reject invalid characters in domains

2026-10-09 00:00:12 +01:00

normalize.go

Reject invalid characters in domains

2026-10-09 00:00:12 +01:00