There is a potentially troublesome denial of service risk linked to a vuln in the Linux 2.4 kernel, concerning the cacheing of routing information.

A Red Hat advisory on the problem explains: "A remote attacker could send packets with carefully chosen, forged source addresses in such a way as to make every routing cache entry get hashed into the same hash chain. The result would be that the kernel would use a disproportionate amount of processor time to deal with new packets, resulting in a remote denial of service attack."

Red Hat has issued updated kernel packages.

An advisory by security outfit Secunia provides a list of other affected Linux distributions (too numerous to list here). An official patch or update for the Linux Kernel is yet to be made available, according to Secunia.

However workarounds are available and there's little evidence that the vulnerability has been maliciously exploited, at least for now. ®