The kdenetwork packages contain networking applications for the K Desktop Environment (KDE). Krfb Desktop Sharing, which is a part of the kdenetwork package, is a server application that allows session sharing between users. Krfb uses the LibVNCServer library.
A NULL pointer dereference flaw was found in the way LibVNCServer handled certain ClientCutText message. A remote attacker could use this flaw to crash the VNC server by sending a specially crafted ClientCutText message from a VNC client. (CVE-2014-6053)
A divide-by-zero flaw was found in the way LibVNCServer handled the scaling factor when it was set to "0". A remote attacker could use this flaw to crash the VNC server using a malicious VNC client. (CVE-2014-6054)
Two stack-based buffer overflow flaws were found in the way LibVNCServer handled file transfers. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client. (CVE-2014-6055)
Red Hat would like to thank oCERT for reporting these issues. oCERT acknowledges Nicolas Ruff as the original reporter.
Note: Prior to this update, the kdenetwork packages used an embedded copy of the LibVNCServer library. With this update, the kdenetwork packages have been modified to use the system LibVNCServer packages. Therefore, the update provided by RHSA-2014:1826 must be installed to fully address the issues in krfb described above.
All kdenetwork users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. All running instances of the krfb server must be restarted for this update to take effect.