The remote host is missing an update to ikiwiki announced via advisory DSA 2020-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202020-1

Ivan Shmakov discovered that the htmlscrubber component of ikwiki, a wiki compiler, performs insufficient input sanitization on data:image/svg+xml URIs. As these can contain script code this can be used by an attacker to conduct cross-site scripting attacks. For the stable distribution (lenny), this problem has been fixed in version 2.53.5. For the testing distribution (squeeze), this problem has been fixed in version 3.20100312. For the unstable distribution (sid), this problem has been fixed in version 3.20100312.