MHonArc 2.5.2 and earlier does not properly filter Javascript from archived e-mail messages, which could allow remote attackers to execute script in web clients by (1) splitting the SCRIPT tag into smaller pieces, (2) including the script in a SRC argument to an IMG tag, or (3) using "&={script}" syntax.
Exploitability
AV:NAC:LAu:NImpact
C:PI:PA:P7.5/AV:N/AC:L/Au:N/C:P/I:P/A:P