Cisco released a trio of updates on Wednesday. The advisories cover denial of service vulnerabilities in IOS Secure Shell and its Secure Control Engine software. The escalation update involves Cisco's voice engine portal software.

The network giant states that it discovered all three vulnerabilities itself but the timing of the releases, on the day before Sebastian Muniz of CORE Security demoed proof of concept router rootkit software, may be more than simply coincidental. As researchers at the SANS Institute's Internet Storm Centre note, the IOS Secure Shell bug allows "spurious memory access".

"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 should not be taken lightly," writes ISC staffer George Bakos.

Cisco launched a twice-yearly patching cycle for IOS vulnerabilities back in March. The IOS Secure Shell falls outside this cycle, providing further fuel for conspiracy theorists.

Cisco's advisories can be found here, here and here. ®

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