CVE-2021-34737 Cisco IOS XR Software DHCP Version 4 Server Denial of Service Vulnerability
Remote attackers can crash the DHCPv4 server process via malformed messages, causing temporary service unavailability on Cisco IOS XR devices.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-34737?
CVE-2021-34737 is a medium-severity vulnerability in Cisco Ios Xr, published on 9 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the DHCP version 4 (DHCPv4) server feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to trigger a crash of the dhcpd process, resulting in a denial of service (DoS) condition. This vulnerability exists because certain DHCPv4 messages are improperly validated when they are processed by an affected device. An attacker could exploit this vulnerability by sending a malformed DHCPv4 message to an affected device. A successful exploit could allow the attacker to cause a NULL pointer dereference, resulting in a crash of the dhcpd process. While the dhcpd process is restarting, which may take up to approximately two minutes, DHCPv4 server services are unavailable on the affected device. This could temporarily prevent network access to clients that join the network during that time period. Note: Only the dhcpd process crashes and eventually restarts automatically. The router does not reload.
Weakness: CWE-476
Which versions are affected by CVE-2021-34737?
It affects 1 product.
Products include Cisco Ios Xr.
How do I fix CVE-2021-34737?
No fix has been published for CVE-2021-34737 yet. Limit exposure of the affected software until one is available.
Is CVE-2021-34737 being exploited?
There is no known exploitation of CVE-2021-34737 in the wild and no public exploit code.
Other vulnerabilities in Cisco Ios Xr
- CVE-2020-3118 Cisco IOS XR Software Discovery Protocol Format String
- CVE-2020-3569 Cisco IOS XR Software DVMRP Memory Exhaustion
- CVE-2020-3566 Cisco IOS XR Software DVMRP Memory Exhaustion
- CVE-2010-3035 Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service
- CVE-2022-20821 Cisco IOS XR Open Port
Sources
Also known as GHSA-x6m9-rgr7-fm6p.