High severity · published Sep 2, 2026
CVE-2026-20277
Cisco IOS XR Software Security Hardening Release: September 2026
8.2
CVSS
0.4%
EPSS
No
On KEV
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-2026-20277 are related to protection mechanism failure issues that are grouped under the Common Weakness Enumeration (CWE) CWE-693.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 35% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CI
Cisco IOS XR Software · Cisco
6.5.29; 7.0.1; 6.5.26; 6.5.25; 6.5.28; 6.5.90; +34 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-20277
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-20277
sec.cloudapps.cisco.com
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxr-qg64NcM
www.cve.org
https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification
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CVE-2026-20279
Cisco IOS XR Software Security Hardening Release: September 2026