# CVE-2026-20279: Cisco IOS XR Software Security Hardening Release: September 2026

> Improper access control in Cisco IOS XR allows attackers to bypass security restrictions, requiring a software patch.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 Sep 2026
- **Updated:** 18 Sep 2026
- **Also known as:** GHSA-ff4v-8pj2-jrwh

## What is CVE-2026-20279?

CVE-2026-20279 is a critical missing authorization vulnerability in Cisco IOS XR Software, 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-2026-20279 are related to improper access control issues that are grouped under the Common Weakness Enumeration (CWE) CWE-284.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2026-20279?


## How do I fix CVE-2026-20279?

No fix has been published for CVE-2026-20279 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-20279 being exploited?

There is no known exploitation of CVE-2026-20279 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20279 and fix it if it is affected.

What it is: CVE-2026-20279 is a critical missing authorization vulnerability in Cisco IOS XR Software, published on 2 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-20279 in the wild and no public exploit code.

Affected product: Cisco IOS XR Software. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-20279/ (Markdown: https://insights.sbomify.com/CVE-2026-20279/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20279
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20279
- OSV: https://osv.dev/vulnerability/CVE-2026-20279

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20279/
Summaries are generated and may contain mistakes; the official description above is the record.