CVE-2026-20274 Cisco IOS XR Software Security Hardening Release: September 2026
Cisco IOS XR contains improper resource control flaws that could allow attackers to cause a denial of service condition.
- 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-2026-20274?
CVE-2026-20274 is a critical denial of service vulnerability in Cisco Ios Xr, published on 2 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XR Software engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20274 are related to improper resource control issues that are grouped under the Common Weakness Enumeration (CWE) CWE-664.
Weakness: CWE-664
Which versions are affected by CVE-2026-20274?
It affects 1 product.
Products include Cisco Ios Xr.
How do I fix CVE-2026-20274?
No fix has been published for CVE-2026-20274 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-20274 being exploited?
There is no known exploitation of CVE-2026-20274 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-3m84-xhjg-xc55.