Dhcpcd: dhcpcd infinite loop and out-of-bounds read via zero-length ipv6 nd option in router advertisement handling
A flaw was found in dhcpcd's IPv6 Neighbor Discovery Router Advertisement processing. A specially crafted IPv6 Router Advertisement containing a zero-length Neighbor Discovery option can bypass validation during packet storage and later be reparsed without adequate validation, causing the parser to enter a non-advancing loop. Successful exploitation may result in excessive CPU consumption, leading to a denial of service.
Until an updated package is available, administrators should disable IPv6 Router Advertisement processing on interfaces where it is not required or restrict acceptance of untrusted ICMPv6 Router Advertisements using appropriate network filtering.
Systems that rely on IPv6 Stateless Address Autoconfiguration (SLAAC) or Router Advertisement-based network configuration should carefully evaluate the operational impact before applying these mitigations.
Exploits
Credits
Red Hat would like to thank AISLE Research for reporting this issue.