Callum Stewart

Director (Offensive Security Services)

As a Technical Team Manager with over ten years’ security experience, Callum has a wide range of experience in several technical roles.

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Highlights

Career highlights

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As a Technical Team Manager with over ten years’ security experience, Callum has a wide range of experience in several technical roles. His role at Bastion Security focuses on technical testing, as well as configuration and design reviews. Callum covers a wide range of testing, including penetration testing of websites, applications and APIs, firewall configuration reviews, host security configuration reviews, external perimeter reviews and application configuration reviews.

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Nokia WS-NOC and NSP Vulnerabilities

During a security engagement, Steve Nyan Lin discovered numerous vulnerabilities within WS-NOC and NSP which could lead to a low-privileged user accessing administrative functionalities, cross-site scripting and open redirection.

Access Token Exposure in URL Parameters in GridTime™ 3000 GNSS Time Server - (CVE-2026-12620)

During a security engagement, Leo Diamat discovered that the GridTime 3000 GNSS Time Server web application transmitted session access tokens via URL query string parameters on multiple endpoints.

Cross-Site Scripting (XSS) Vulnerability on Several Endpoints by Utilising Cross-Site Request Forgery (CSRF) in GridTime™ 3000 GNSS Time Server - (CVE-2026-12619)

During a security engagement, Leo Diamat discovered that multiple endpoints in the GridTime 3000 GNSS Time Server web application were vulnerable to reflected Cross-Site Scripting (XSS) via an unsanitised token parameter.

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