High

Stack-Based Buffer Overflow in Zyxel GS1900 Series CGI Program

IdentifiersCVE-2026-7273CWE-121· Stack-based Buffer Overflow

CVE-2026-7273 is a stack-based buffer overflow in the CGI program used by Zyxel GS1900 series switch firmware. The flaw affects GS1900 series models including GS1900-8, GS1900-8HP, GS1900-10HP, GS1900-16, GS1900-24, GS1900-24E, GS1900-24EP, GS1900-24HPv2, GS1900-48, and GS1900-48HPv2 on vulnerable firmware revisions up to their listed 2.90(... .1)C0 builds, including GS1900-48HPv2 through 2.90(ABTQ.1)C0. Zyxel states that a LAN-based, unauthenticated attacker can trigger the vulnerability by sending a crafted HTTP request to the device management interface. Successful exploitation could corrupt stack memory in the CGI component and potentially lead to execution of operating system commands on the switch.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation may allow a LAN-adjacent unauthenticated attacker to execute OS commands on the affected switch. Given the published CVSS v3.1 vector AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, the expected impact includes full compromise of confidentiality, integrity, and availability of the device. In practical terms, compromise of a managed switch can enable device takeover, service disruption, configuration tampering, interception or manipulation of network traffic traversing the switch, and use of the switch as a foothold for further movement inside the local network.

Mitigation

If you can’t patch tonight, do this now.

Until firmware updates can be applied, restrict HTTP management access to trusted hosts on the local network only. Limit exposure of the switch management interface through network segmentation, ACLs, or dedicated management VLANs, and prevent untrusted LAN users from reaching the web administration service. If operationally feasible, disable or tightly control web-based management access until patching is complete.

Remediation

Patch, then assume compromise.

Apply Zyxel's patched firmware for the affected GS1900 model. Reported fixed versions include: GS1900-8 to 2.90(AAHH.2)C0, GS1900-8HP to 2.90(AAHI.2)C0, GS1900-10HP to 2.90(AAZI.2)C0, GS1900-16 to 2.90(AAHJ.2)C0, GS1900-24 to 2.90(AAHL.2)C0, GS1900-24E to 2.90(AAHK.2)C0, GS1900-24EP to 2.90(ABTO.2)C0, GS1900-24HPv2 to 2.90(ABTP.2)C0, GS1900-48 to 2.90(AAHN.2)C0, and GS1900-48HPv2 to 2.90(ABTQ.2)C0. Zyxel advises customers to install the updated firmware without delay.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

Zyxel CommunicationsGs1900-48hpv2 Firmwareoperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

7 SOURCESView more in app

security online infoNews

Jun 18, 2026

Zyxel GS1900 Vulnerability: Buffer Overflow Risks RCE

A stack-based buffer overflow in the CGI program of Zyxel GS1900 switch firmware that could allow a LAN-based unauthenticated attacker to execute OS commands via a crafted HTTP request and potentially take control of affected hardware.

cvefeed high severityNews

Jun 16, 2026

CVE-2026-7273 - Zyxel GS1900-48HPv2 Stack-Based Buffer Overflow Remote Code Execution

A stack-based buffer overflow in the CGI program of Zyxel GS1900-48HPv2 firmware that may allow a LAN-based unauthenticated attacker to execute OS commands via a crafted HTTP request.

zyxelNews

Jan 1, 2026

Zyxel security advisory for stack-based buffer overflow vulnerability in GS1900 series switches | Zyxel Networks

A stack-based buffer overflow in the CGI program of Zyxel GS1900 series switch firmware that could allow a LAN-based unauthenticated attacker to potentially execute OS commands via a crafted HTTP request.

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity4

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-7273

NVD

nvd.nist.gov/vuln/detail/CVE-2026-7273

MITRE CWE · CWE-121

Stack-based Buffer Overflow

zyxel.com

zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-stack-based-buffer-overflow-vulnerability-in-gs1900-series-switches-06-16-2026