On Sun, Jun 30, 2024 at 23:08:01 +0100, Tim Woodall wrote: > According to this > https://support.trustwave.com/kb/KnowledgebaseArticle10016.aspx > > bare CRs aren't allowed in emails but this has always worked. > > I'm only likely to have cron generating emails like this. > > Strange that this would have been changed in a stable release. It > doesn't seem to have been a security update.
It looks like it's coming from this change: https://metadata.ftp-master.debian.org/changelogs//main/s/sendmail/sendmail_8.17.1.9-2+deb12u2_changelog * Fix CVE-2023-51765 (Closes: #1059386): sendmail allowed SMTP smuggling in certain configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because sendmail supports <LF>.<CR><LF> but some other popular e-mail servers do not. This is resolved with 'o' in srv_features. I don't know the details of how this leads to a security hole.
