https://bugs.exim.org/show_bug.cgi?id=1926
Bug ID: 1926
Summary: DKIM TXT record parsing too lenient ("\" escaping)
Product: Exim
Version: 4.87
Hardware: x86-64
OS: Linux
Status: NEW
Severity: bug
Priority: medium
Component: DKIM
Assignee: tom@???
Reporter: chibi@???
CC: exim-dev@???
We had a wrongly configured TXT record for one domain that looked like this:
"v=DKIM1\\\; k=rsa\\\; p=..."
When verifying correctly signed mails for this domain Exim (in the receiving,
MX role) vetted them with "[verification succeeded]".
Whereas google.com or other DKIM verification systems took offence to the
triple backslash as opposed to the correct single one.
My (uneducated, non-source checking) guess would be that the parsing inside
Exim just ignores unexpected garbage in the "v=" and "k=" fields or recursively
goes through the escaping sequence until it arrives at a "correct" result.
Christian
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