Zyxel GS1900-48 up to 2.90(ABTQ.1)C0 HTTP stack-based overflow

Summaryinfo

A vulnerability identified as critical has been detected in Zyxel GS1900-48HPv2, GS1900-8, GS1900-8HP, GS1900-10HP, GS1900-16, GS1900-24, GS1900-24E, GS1900-24EP, GS1900-24HPv2 and GS1900-48 up to 2.90(ABTQ.1)C0. This impacts an unknown function of the component HTTP Handler. Performing a manipulation results in stack-based overflow. This vulnerability is known as CVE-2026-7273. Access to the local network is required for this attack. No exploit is available.

Detailsinfo

A vulnerability was found in Zyxel GS1900-48HPv2, GS1900-8, GS1900-8HP, GS1900-10HP, GS1900-16, GS1900-24, GS1900-24E, GS1900-24EP, GS1900-24HPv2 and GS1900-48 up to 2.90(ABTQ.1)C0. It has been classified as critical. This affects some unknown functionality of the component HTTP Handler. The manipulation with an unknown input leads to a stack-based overflow vulnerability. CWE is classifying the issue as CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at zyxel.com. This vulnerability is uniquely identified as CVE-2026-7273 since 04/28/2026. The exploitability is told to be easy. The attack can only be initiated within the local network. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 06/16/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-37030). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• Zyxel

Name

• GS1900-8
• GS1900-8HP
• GS1900-10HP
• GS1900-16
• GS1900-24
• GS1900-24E
• GS1900-24EP
• GS1900-24HPv2
• GS1900-48
• GS1900-48HPv2

Version

• 2.90(ABTQ.1)C0

License

• commercial

Website

• Vendor: https://www.zyxel.com/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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