Cisco IOS XR Software: Improper Control of a Resource Through its Lifetime
CVE-2026-20274 is a critical-severity improper control of a resource through its lifetime vulnerability in Cisco IOS XR Software from Cisco, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Cisco IOS XR Software versions: 6.5.29; 7.0.1; 6.5.26, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.53% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of Cisco IOS XR Software you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco IOS XR Software | 6.5.29; 7.0.1; 6.5.26; 6.5.25; 6.5.28; 6.5.90; 7.1.1; 7.0.90; and 32 more ranges | Not stated |
| Cisco | iOS Xr | 6.5.25; 6.5.26; 6.5.28; 6.5.29; 6.5.31; 6.5.32; 6.5.33; 6.5.35; and 32 more ranges | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (cisco.com).
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Control of a Resource Through its Lifetime
The product does not maintain or incorrectly maintains control over a resource throughout its lifetime of creation, use, and release.
More Improper Control of a Resource Through its Lifetime vulnerabilities (CWE-664)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Cisco IOS XR Software
- 7.5 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 8.2 High severity
- 8.6 High severity
Recent Improper Control of a Resource Through its Lifetime vulnerabilities
- 9.8 Critical severity
- 8.6 High severity
- 7.5 High severity
- 8.8 High severity
- 7.5 High severity
- 8.1 High severity
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