Cisco just had to release the kind of security advisory that no tech company ever wants to have to release. The company disclosed a critical vulnerability in its software. According to the advisory, no workaround is currently available to resolve the issue.

The vulnerability affects ASR 5000 devices running StarOS and Virtualized Packet Core (VPC) systems. It could allow an attacker to create a denial-of-service (DoS) condition or potentially execute arbitrary code, the company said.

Cisco Takes the Heat

The company admitted the problem is “due to unsafe code generation by the ASN1C compiler when creating ASN.1 translation functions that are subsequently included within affected Cisco products.” A malicious actor could exploit the vulnerability by submitting a malicious encoded message that then triggers an affected function.

Cisco ASR 5000 devices running StarOS versions 17.x, 18.x, 19.x, and 20.x are affected, as well as Cisco Virtualized Packet Core systems versions V18.x, V19.x, and V20.x. It’s so serious that US-CERT released a vulnerability note to document the issue as well.

A Critical But Improbable Risk

Although the vulnerability is critical, it is difficult to exploit. Some security professionals consider this sort of attack improbable because of the necessary development.

“To make use of the vulnerability, an attacker would need very specific knowledge of the target device and the ability to insert communications freely into the channel,” Bill Anderson, an encryption expert at OptioLabs, told SecurityWeek. “It would likely take significant effort and resources to achieve an exploit that would reliably open up a telecom system to attack.”

Cisco said it will release fixed software versions for affected products. The company also said its “Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability.”