Critical

CVE-2026-20274 — As part of Cisco's ongoing commitment to proactive security and product quality, the…

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.

Published Sep 2, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database · CNA: psirt@cisco.com

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

—

No EPSS score.

Affects

Cisco

Ios Xr

CVSS base

9.8

Critical · 1 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Cisco Ios Xr).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Cisco	Ios Xr	version 6.5.25version 6.5.26version 6.5.28version 6.5.29version 6.5.31version 6.5.32version 6.5.33version 6.5.35 and 103 more version 6.5.90version 6.5.351version 6.5.352version 6.5.353version 6.7.1version 6.7.2version 6.7.3version 6.7.4version 6.7.35version 6.8.1version 6.8.2version 6.9.1version 6.9.2version 7.0.0version 7.0.1version 7.0.2version 7.0.11version 7.0.12version 7.0.14version 7.0.90version 7.1.1version 7.1.2version 7.1.3version 7.1.15version 7.1.25version 7.2.0version 7.2.1version 7.2.2version 7.2.12version 7.3.1version 7.3.2version 7.3.3version 7.3.4version 7.3.5version 7.3.6version 7.3.15version 7.3.16version 7.3.27version 7.4.1version 7.4.2version 7.4.15version 7.4.16version 7.5.1version 7.5.2version 7.5.3version 7.5.4version 7.5.5version 7.5.12version 7.5.52version 7.6.1version 7.6.2version 7.6.3version 7.6.15version 7.7.1version 7.7.2version 7.7.21version 7.8.1version 7.8.2version 7.8.12version 7.8.22version 7.8.23version 7.9.1version 7.9.2version 7.9.21version 7.10.1version 7.10.2version 7.11.1version 7.11.2version 7.11.21version 24.1.1version 24.1.2version 24.2.1version 24.2.2version 24.2.11version 24.2.20version 24.2.21version 24.3.1version 24.3.2version 24.3.20version 24.3.30version 24.4.1version 24.4.2version 24.4.10version 24.4.15version 24.4.30version 25.1.1version 25.1.2version 25.1.30version 25.2.1version 25.2.2version 25.2.15version 25.2.30version 25.3.1version 25.3.15version 25.4.1version 25.4.2version 25.4.30version 25.4.201version 26.1.1version 26.1.2version 26.2.1version 26.2.100version 26.2.101	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.8	CVSS 3.1	Critical	3.9	5.9	psirt@cisco.com via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: psirt@cisco.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-664

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 15, 2026
CVSS changed · 9.8
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Sep 2, 2026 · psirt@cisco.com

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

2 on the record

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosx
Vendor Advisory, NIST National Vulnerability Database
www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identi
Not Applicable, NIST National Vulnerability Database

Elsewhere on this site

Cisco
every CVE for this vendor

CWE-664
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-20280 Improper Check or Handling of Exceptional Conditions in Cisco Ios Xr Sep 2, 2026
High CVE-2026-20276 As part of Cisco's ongoing commitment to proactive security and product quality, the… Sep 2, 2026
High CVE-2026-20046 Cisco IOS XR Software CLI Privilege Escalation Vulnerability Mar 11, 2026
High CVE-2026-20074 Cisco IOS XR Software Multi-Instance Intermediate System-to-Intermediate System Denial of Service Vulnerability Mar 11, 2026
High CVE-2026-20040 Cisco IOS XR Software CLI Privilege Escalation Vulnerability Mar 11, 2026
High CVE-2023-44487 HTTP/2 Rapid Reset Attack Vulnerability KEV Oct 10, 2023

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No FIRST EPSS score.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-20274 is "As part of Cisco's ongoing commitment to proactive security and product quality, the…", rated Critical. It affects Ios Xr (Cisco); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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