Hi,

Horde IMP v4.3.7 and lower are subject to a cross site scripting (XSS)
vulnerability:

The fetchmailprefs.php script fails to properly sanitize user supplied
input to the 'fm_id' URL parameter. If exploited, injected code will be
persistent (persistent XSS) and will execute once the user (manually)
accesses mail fetching preferences.

The following URL can be used as a proof of concept:
> [path_to_horde_imp]/fetchmailprefs.php?actionID=fetchmail_prefs_save&fm_driver=imap&fm_id=zzz%22%3E%3Cscript%3Ealert%28%27XSS%27%29%3C%2Fscript%3E%3Cx+y%3D%22&fm_protocol=pop3&fm_lmailbox=INBOX&save=Create

Prior authentication to IMP is required for immediate exploitation.
Follow-up authentication is also possible if the victims' IMP
configuration has folder maintenance options disabled.

This issue has been fixed by Jan Schneider of the Horde Project:
> https://git.horde.org/diff.php/imp/fetchmailprefs.php?rt=horde&r1=1.39.4.10&r2=1.39.4.11

According to him, Horde IMP v4.3.8 (or a release candidate) which fixes
this issue is to be released within the week. Release announcements will
likely be communicated through
https://lists.horde.org/mailman/listinfo/announce

Credits for this discovery:

Moritz Naumann
Naumann IT Security Consulting, Berlin, Germany
https://moritz-naumann.com

Thanks for reading,

Moritz

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