Virtual Event: Threat Detection and Incident Response Summit - Watch Sessions
Connect with us

Hi, what are you looking for?



Cisco Patches Actively Exploited Flaws in Carrier-Grade Routers

Cisco this week released patches for two high-severity vulnerabilities in IOS XR software that have been actively exploited in attacks for over a month.

Cisco this week released patches for two high-severity vulnerabilities in IOS XR software that have been actively exploited in attacks for over a month.

Tracked as CVE-2020-3566 and CVE-2020-3569 and featuring a CVSS score of 8.6, the two flaws were made public in late August, when Cisco revealed that hackers were already targeting them in attacks.

The two issues were identified in the Distance Vector Multicast Routing Protocol (DVMRP) feature of IOS XR and could be exploited without authentication to cause the Internet Group Management Protocol (IGMP) process to exhaust process memory and crash.

The bugs, Cisco explains, exist because IGMP packets are not handled correctly, meaning that crafted IGMP traffic can be sent to the affected devices to trigger them. A successful exploit would immediately crash the IGMP process or cause memory exhaustion, thus impacting the stability of other processes, including those of routing protocols.

“In the case of an immediate IGMP process crash, it is not necessary to manually restart the IGMP process because the system has already performed that action. This automated restart will recover the consumed memory,” the company notes in an advisory.

All Cisco devices running IOS XR are affected, “if an active interface is configured under multicast routing,” and if DVMRP traffic is being received, Cisco explains.

Administrators can use the show igmp interface and show igmp traffic commands to determine whether multicast routing is enabled and whether the device is receiving DVMRP traffic. Furthermore, they can employ rate limiter and access control methods to mitigate the memory exhaustion.

Advertisement. Scroll to continue reading.

This week, Cisco announced that software updates designed to address these vulnerabilities are available for ASR9K-PX, ASR9K-X64, CRS, and NCS5500 platforms.

Related: Cisco Says Hackers Targeting Zero-Days in Carrier-Grade Routers

Related: WordPress ‘File Manager’ Plugin Patches Critical Zero-Day Exploited in Attacks

Related: Twitter Says Bug Leading to API Key Leak Patched

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

Click to comment

Daily Briefing Newsletter

Subscribe to the SecurityWeek Email Briefing to stay informed on the latest threats, trends, and technology, along with insightful columns from industry experts.

SecurityWeek’s Threat Detection and Incident Response Summit brings together security practitioners from around the world to share war stories on breaches, APT attacks and threat intelligence.


Securityweek’s CISO Forum will address issues and challenges that are top of mind for today’s security leaders and what the future looks like as chief defenders of the enterprise.


Expert Insights

Related Content


Less than a week after announcing that it would suspended service indefinitely due to a conflict with an (at the time) unnamed security researcher...

Data Breaches

OpenAI has confirmed a ChatGPT data breach on the same day a security firm reported seeing the use of a component affected by an...


The changing nature of what we still generally call ransomware will continue through 2023, driven by three primary conditions.


Luxury retailer Neiman Marcus Group informed some customers last week that their online accounts had been breached by hackers.


As it evolves, web3 will contain and increase all the security issues of web2 – and perhaps add a few more.


A recently disclosed vBulletin vulnerability, which had a zero-day status for roughly two days last week, was exploited in a hacker attack targeting the...


Satellite TV giant Dish Network confirmed that a recent outage was the result of a cyberattack and admitted that data was stolen.


Zendesk is informing customers about a data breach that started with an SMS phishing campaign targeting the company’s employees.