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

82
Patch now
HIGH 8.8EXPLOITEDMITIGATEMITIGATEMITIGATE

CVE-2026-7273 is a high-severity flaw (CVSS 8.8) affecting gs1900-8 firmware, gs1900-8hp firmware, gs1900-10hp firmware, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

  • High severity
  • Exploited in the wild (CISA KEV)
  • Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score8.8 (High)
Attack vectorAdjacent network
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance2.5% (top 15%)
CISA exploited listYes, fix due 2026-09-24
WeaknessCWE-121
Published2026-06-16
Last modified2026-09-22
Publisher (CNA): Zyxel Corporation · Vendor: zyxel

Last updated 2026-09-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

zyxel gs1900-8 firmware MITIGATE
Affected: < 2.90\(aahh.2\)c0
Fixed in: 2.90\(aahh.2\)c0
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
zyxel gs1900-8hp firmware MITIGATE
Affected: < 2.90\(aahi.2\)c0
Fixed in: 2.90\(aahi.2\)c0
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
zyxel gs1900-10hp firmware MITIGATE
Affected: < 2.90\(aazi.2\)c0
Fixed in: 2.90\(aazi.2\)c0
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
zyxel gs1900-16 firmware MITIGATE
Affected: < 2.90\(aahj.2\)c0
Fixed in: 2.90\(aahj.2\)c0
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
zyxel gs1900-24 firmware MITIGATE
Affected: < 2.90\(aahl.2\)c0
Fixed in: 2.90\(aahl.2\)c0
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
zyxel gs1900-24e firmware MITIGATE
Affected: < 2.90\(aahk.2\)c0
Fixed in: 2.90\(aahk.2\)c0
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.
Fedora 46 · retext · FIXED · 8.1.0-1.fc46 · FEDORA-2026-0602a84203 · source
sudo dnf upgrade --advisory=FEDORA-2026-0602a84203
Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-7273?

gs1900-8 firmware: mitigate or apply the listed mitigation; gs1900-8hp firmware: mitigate or apply the listed mitigation; gs1900-10hp firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-7273 being exploited?

Yes. CVE-2026-7273 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2026-7273 affect?

CVE-2026-7273 affects gs1900-8 firmware, gs1900-8hp firmware, gs1900-10hp firmware. Severity is high (CVSS 8.8). 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 c

How urgent is CVE-2026-7273?

Priority 82/100. High severity; Exploited in the wild (CISA KEV); Public exploit reference

Software pages

Zyxel vulnerabilities

References

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