Risk: Medium
Some Denial of Service vulnerabilities have been found in ISC BIND versions 9.2.x and 9.3.x.
An assertion error within the processing of SIG queries can be exploited to crash either a recursive server when more than one SIG (covered) Resource Record set (RRset) is returned, or an authoritative server serving a RFC 2535 DNSSEC zone where there are multiple SIG (covered) RRsets. Exposure can be minimised by restricting sources that can ask for recursion.
An error in the handling of multiple recursive queries can be exploited to trigger an INSIST failure by causing the response to the query to arrive after all clients looking for the response have left the recursion queue. Exposure can be minimised by restricting sources that can ask for recursion.
According to the vendor, the vulnerabilities are probably not exploitable in the 9.2.x branch. However, a patch has been issued and is available at: