While the "Exploitation and Public Announcements" portion of all three advisories states that the vulns were discovered in-house, it's a pretty safe bet that a fair number of security "researchers" are feverishly reverse engineering the updates to develop exploits for private use and/or public release.
Anytime we see a "spurious memory access" leading to a denial of service, thoughts immediately go to arbitrary code execution. There is no evidence that this is possible, but in light of the recent work in IOS rootkits, vulns in Cisco devices sould not be taken lightly. Sebastian Muniz of CORE Security is scheduled to release a proof of concept Cisco IOS rootkit tomorrow at EuSecWest. Stand by for more details.