# CVE-2026-7273: Zyxel GS1900 Series Switches Stack-Based Buffer Overflow

> A stack-based buffer overflow in the CGI program allows unauthenticated LAN attackers to execute OS commands via crafted HTTP requests.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 21 Sep 2026 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Jun 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-rrv4-8jq5-8j78

## What is CVE-2026-7273?

CVE-2026-7273 is a high-severity memory corruption vulnerability in Zyxel GS1900-10HP firmware, published on 16 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A stack-based buffer overflow vulnerability in the CGI program of Zyxel GS1900-48HPv2 firmware versions through 2.90(ABTQ.1)C0 could allow a LAN-based, unauthenticated attacker to exploit the flaw and potentially execute OS commands via a crafted HTTP request.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-7273?

It affects 10 products.


Products: Zyxel Gs1900-10hp Firmware, Zyxel Gs1900-16 Firmware, Zyxel Gs1900-24 Firmware, Zyxel Gs1900-24e Firmware, Zyxel Gs1900-24ep Firmware, Zyxel Gs1900-24hpv2 Firmware, Zyxel Gs1900-48 Firmware, Zyxel Gs1900-48hpv2 Firmware, Zyxel Gs1900-8 Firmware, Zyxel Gs1900-8hp Firmware.

## How do I fix CVE-2026-7273?

No fix has been published for CVE-2026-7273 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 24 Sep 2026.

## Is CVE-2026-7273 being exploited?

Yes. Attackers have exploited CVE-2026-7273 in the wild since at least 21 Sep 2026.

## Other vulnerabilities in Zyxel GS1900-10HP firmware

- [CVE-2019-15800](https://insights.sbomify.com/CVE-2019-15800/): Command injection in n/a (critical 9.8)
- [CVE-2015-5988](https://insights.sbomify.com/CVE-2015-5988/): Hardcoded credentials in n/a (critical 9.8)
- [CVE-2015-5989](https://insights.sbomify.com/CVE-2015-5989/): Auth bypass in n/a (critical 9.8)
- [CVE-2019-15803](https://insights.sbomify.com/CVE-2019-15803/): Auth bypass in n/a (critical 9.1)
- [CVE-2019-15799](https://insights.sbomify.com/CVE-2019-15799/): Privilege escalation in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-7273 and fix it if it is affected.

What it is: CVE-2026-7273 is a high-severity memory corruption vulnerability in Zyxel GS1900-10HP firmware, published on 16 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2026-7273 in the wild since at least 21 Sep 2026.

Affected product: Zyxel GS1900-10HP firmware. 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-2026-7273/ (Markdown: https://insights.sbomify.com/CVE-2026-7273/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-7273
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-7273
- OSV: https://osv.dev/vulnerability/CVE-2026-7273

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-7273/
Summaries are generated and may contain mistakes; the official description above is the record.