The remote host is missing an update as announced via advisory SSA:2008-119-01.

https://secure1.securityspace.com/smysecure/catid.html?in=SSA:2008-119-01

New libpng packages are available for Slackware 8.1, 9.0, 9.1, 10.0, 10.1, 10.2, 11.0, 12.0, and -current to fix a security issue. More details about this issue may be found in the Common Vulnerabilities and Exposures (CVE) database: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-1382 Additional information can be found in the libpng source, or in this file on the libpng FTP site: ftp://ftp.simplesystems.org/pub/libpng/png/src/libpng-1.2.27-README.txt