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

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

CISA required action CISA

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

US federal deadline: Sep 24, 2026 — passed 21 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Zyxel GS1900-10HP firmware, Zyxel GS1900-16 firmware, Zyxel GS1900-24 firmware…).
2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
4. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-121 · Stack-based Buffer Overflow

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

EPSS over time FIRST

Oct 12, 2026 → Oct 14, 2026 · 3 reading(s) · max 2.50%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
• Hunt retroactively in logs from before Sep 21, 2026 (KEV listing): exploitation may have started earlier.

Timeline

What happened to this CVE, newest first.

• 2026
• Affected products added · zyxel/gs1900-8 firmware, zyxel/gs1900-8hp firmware, zyxel/gs1900-10hp firmware, zyxel/gs1900-16 firmware, zyxel/gs1900-2
  Oct 13, 2026 · NIST National Vulnerability Database
• Source status changed · Published → Analyzed
  Oct 13, 2026 · NIST National Vulnerability Database
• Record published
  Oct 13, 2026
• Affected products added · zyxel/gs1900-48hpv2 firmware, zyxel/gs1900-8 firmware, zyxel/gs1900-8hp firmware, zyxel/gs1900-10hp firmware, zyxel/gs19
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• CVSS changed · 8.8
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Source status changed · → Published
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• SSVC assessment updated
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Added to CISA KEV (detected)
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• Record created in this database
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• Added to CISA KEV catalog
  Sep 20, 2026 · CISA
• CVE published
  Jun 16, 2026 · Zyxel

Source activity

Repeated readings are counted rather than listed.

• 2× References added · Oct 13, 2026 – Oct 13, 2026
• 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

5 on the record

• www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-sta
  vendor-advisory, Vendor Advisory, CVE Program (cve.org) e CISA ADP
• nvd.nist.gov/vuln/detail/CVE-2026-7273
  GitHub Security Advisories
• www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordp
  Exploit, Third Party Advisory, GitHub Security Advisories
• github.com/advisories/GHSA-rrv4-8jq5-8j78
  GitHub Security Advisories
• www.cisa.gov/known-exploited-vulnerabilities-catalog
  Third Party Advisory, US Government Resource, GitHub Security Advisories

Elsewhere on this site

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No fixed version, patch or mitigation documented.
• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-7273 is "Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability", rated High. It affects GS1900-10HP firmware (Zyxel); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 8.8 describes technical severity. EPSS 2.50% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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