---
title: "Security digest: September 21, 2026"
url: https://erroneo.us/security/2026-09-21/
description: "September 21, 2026 vulnerability digest: 1 CISA KEV addition (Zyxel). What to patch and who can relax."
type: security-digest-day
section: "Security Digest"
date_published: 2026-09-21
date_modified: 2026-09-21
publisher: erroneo.us
author: erroneo.us Security Desk
license: All rights reserved. Quote with attribution and a link.
---

# Security digest: September 21, 2026

1 known exploited (cisa kev) addition.

## Take stock

- Do you run any of these? Zyxel GS1900 Series Switches. They are being exploited in the wild (CISA KEV). Patch or mitigate if you do; CISA’s federal deadline is 2026-09-24.
- None of it touches your stack? Then there is nothing to do today. That is a result, not a failure to read carefully.

## Known exploited (CISA KEV)

- [CVE-2026-7273](https://erroneo.us/security/cve/CVE-2026-7273/index.md) Zyxel GS1900 Series Switches: Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability (CISA due 2026-09-24)

## Critical advisories

None.

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Source page: https://erroneo.us/security/2026-09-21/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt