Security Resilience

CVE-2026-7273

Memory Safety in Zyxel Gs1900-8 Firmware ≤ 2.90\(aahh.2\)c0

CISA KEVActive ExploitationEUVD ExploitedPublic PoCMemory Safety
Published
16 June 2026
Modified
25 October 2026
KEV Added
21 September 2026
Patch / advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.028 86th percentile
Risk Priority 90 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). EPSS, Forum of Incident Response and Security Teams (FIRST), epss.first.org. Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-7273 is a high-severity Stack-based Buffer Overflow (CWE-121) vulnerability in Zyxel Gs1900-8 Firmware. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 14% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

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.

CWE(s)
KEV Date Added
21 September 2026

Related Threats

MITRE ATT&CK Enterprise Techniques

MITRE ATT&CK v20.0

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-38270Same product: Zyxel Gs1900-8 Firmware
CVE-2024-8881Same product: Zyxel Gs1900-8 Firmware
CVE-2024-8882Same product: Zyxel Gs1900-8 Firmware
CVE-2017-6884Same vendor: Zyxelboth on KEV
CVE-2024-11667Same vendor: Zyxelboth on KEV
CVE-2023-27992Same vendor: Zyxelboth on KEV
CVE-2022-30525Same vendor: Zyxelboth on KEV
CVE-2020-9054Same vendor: Zyxelboth on KEV
CVE-2024-40890Same vendor: Zyxelboth on KEV
CVE-2023-28771Same vendor: Zyxelboth on KEV

Affected Assets

zyxel
gs1900-8 firmware
≤ 2.90\(aahh.2\)c0
zyxel
gs1900-8hp firmware
≤ 2.90\(aahi.2\)c0
zyxel
gs1900-10hp firmware
≤ 2.90\(aazi.2\)c0
zyxel
gs1900-16 firmware
≤ 2.90\(aahj.2\)c0
zyxel
gs1900-24 firmware
≤ 2.90\(aahl.2\)c0
zyxel
gs1900-24e firmware
≤ 2.90\(aahk.2\)c0
zyxel
gs1900-24ep firmware
≤ 2.90\(abto.2\)c0
zyxel
gs1900-24hpv2 firmware
≤ 2.90\(abtp.2\)c0
zyxel
gs1900-48 firmware
≤ 2.90\(aahn.2\)c0
zyxel
gs1900-48hpv2 firmware
≤ 2.90\(abtq.2\)c0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 2 hardening rules · 2 OS baselines
Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5)

Our mappings, made for this CVE.

Developer testing and analysis can discover stack-buffer overflows before deployment.

Input validation directly stops untrusted data from exceeding stack buffer bounds.

Memory-protection mechanisms limit the ability to execute injected code after a stack overflow.

Secure-engineering principles include bounds-checked coding and safe buffer handling that avoid introducing the flaw.

Mitigating Controls (NIST CSF 2.0)

Our mappings, derived directly from the weakness types (CWEs) cited in the NVD entry via our CWE→CSF cross-walk — links open the control.

PR.PS-06 mostly match
blocks

Secure-development practices directly prevent introduction of stack buffer overflows.

ID.RA-01 partial match
blocks

Vulnerability scanning can discover stack buffer overflows but does not prevent their introduction.

PR.PS-02 partial match
blocks

Patching eliminates known instances of the weakness after discovery.

Mitigating Controls (ISO/IEC 27001:2022 Annex A)

Our mappings, derived directly from the weakness types (CWEs) cited in the NVD entry via our CWE→ISO cross-walk — links open the control.

finds

Security testing (fuzzing, static analysis) detects stack overflows before release.

prevents

Secure coding standards explicitly forbid unsafe buffer handling that causes CWE-121.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over our cross-walk; rows rated `none` are excluded, and each rule says how its mapping was checked.

Definition changed on 29 October 2026. Until then this section listed every rule rated above none, partial included. From that date it lists rules whose mapping is rated full or mostly and checked at llm_unverified or higher; partial mappings show when you ask.

No rule maps to these weaknesses at full or mostly. Tick the option above to see the partial mappings.

Oracle Linux 8 (1 partial rule)
  • V-248594 OL 8 must implement address space layout randomization (ASLR) to protect its memory from unauthorized code execution. blocks CWE-121
Oracle Linux 9 (1 partial rule)
  • V-271452 OL 9 must use a Linux Security Module configured to enforce limits on system services. blocks CWE-121

References