Senior Application Security Specialist
We are looking for junior application security specialists to join a growing security team at
Xsolla. This is a hands-on role where you will work closely with senior specialists to identify,
assess, and help remediate security vulnerabilities across our products and infrastructure.
You will be involved in day-to-day AppSec work - code reviews, vulnerability triage, threat
modeling, and security testing. You are curious, detail-oriented, and eager to develop deep
expertise in application security. You do not need to have all the answers, but you ask the right
questions and follow through.
This is a strong learning environment. You will be exposed to real-world security challenges in a
payment platform operating at scale, and supported by experienced security specialists who will
help you grow.
Evaluate validity, calculate real severity, and escalate appropriately with clear written
summaries.
Assist with Vulnerability Assessments - Participate in security assessments of web
applications and APIs. Help identify and document risks in new features and existing
systems.
Write Clear Security Documentation - Document findings, reproduce steps, and
remediation guidance in a way that engineering teams can act on.
Support Threat Modeling - Participate in threat modeling sessions. Learn to identify
trust boundaries, data flows, and attack surfaces in system designs.
Monitor Security Tools - Help operate SAST, DAST, and dependency scanning tooling.
Track findings, reduce noise, and support remediation workflows.
Support Code Reviews - Review code for common vulnerability classes under guidance
of senior specialists. Learn to identify security issues across PHP, Python, and Go
codebases.
Stay Current - Follow developments in the security community. Bring awareness of new
vulnerability classes, CVEs, and attack techniques relevant to our stack.
OWASP Top 10, CSRF, XSS, IDOR, SQL injection, open redirect, authentication and
session management weaknesses. You understand root causes, not just names.
Web and Browser Fundamentals - Solid understanding of how web applications work:
HTTP request/response cycle, client-server model, REST APIs, how browsers handle
same-origin policy, cookies and their attributes, and CORS. This is the foundation
everything else builds on.
Security Testing Tools - Hands-on experience with Burp Suite or similar web
application security testing tools. You have used them to intercept, modify, and replay
requests - not just run automated scans.
Vulnerability Documentation - Able to reproduce a vulnerability and write it up clearly:
reproduction steps, proof of concept, and impact statement. Findings that engineering
teams cannot reproduce or understand do not get fixed.
Secure Development Awareness - Familiarity with foundational secure coding
concepts: input validation, output encoding, parameterized queries, and least privilege.
Code Readability - Ability to read and follow code in at least one language relevant to
web security - PHP, Python, JavaScript, or Go. You don't need to be a developer, but you
need to follow logic and spot security-relevant patterns.
Analytical Thinking - You reason through problems methodically. You can explain not
just what a vulnerability is but why it exists, how it is exploited, and what fixing it
actually requires.
Clear Written Communication - You write findings and summaries that are precise,
reproducible, and useful to the engineers who need to act on them.
Curiosity and Initiative - You dig into problems rather than stopping at the surface.
When something looks wrong, you investigate before concluding.
Basic scripting ability for automation - Python or Bash
Familiarity with CI/CD pipelines and where security tooling fits
Exposure to cloud environments - GCP, AWS, or Azure
Relevant coursework or certifications - eWPT, CEH, or similar entry-level credentials
Xsolla. This is a hands-on role where you will work closely with senior specialists to identify,
assess, and help remediate security vulnerabilities across our products and infrastructure.
You will be involved in day-to-day AppSec work - code reviews, vulnerability triage, threat
modeling, and security testing. You are curious, detail-oriented, and eager to develop deep
expertise in application security. You do not need to have all the answers, but you ask the right
questions and follow through.
This is a strong learning environment. You will be exposed to real-world security challenges in a
payment platform operating at scale, and supported by experienced security specialists who will
help you grow.
Responsibilities
Triage Security Findings - Assess incoming bug bounty reports and scanner findings.Evaluate validity, calculate real severity, and escalate appropriately with clear written
summaries.
Assist with Vulnerability Assessments - Participate in security assessments of web
applications and APIs. Help identify and document risks in new features and existing
systems.
Write Clear Security Documentation - Document findings, reproduce steps, and
remediation guidance in a way that engineering teams can act on.
Support Threat Modeling - Participate in threat modeling sessions. Learn to identify
trust boundaries, data flows, and attack surfaces in system designs.
Monitor Security Tools - Help operate SAST, DAST, and dependency scanning tooling.
Track findings, reduce noise, and support remediation workflows.
Support Code Reviews - Review code for common vulnerability classes under guidance
of senior specialists. Learn to identify security issues across PHP, Python, and Go
codebases.
Stay Current - Follow developments in the security community. Bring awareness of new
vulnerability classes, CVEs, and attack techniques relevant to our stack.
What You Bring
Web Security Fundamentals - Solid understanding of common vulnerability classes:OWASP Top 10, CSRF, XSS, IDOR, SQL injection, open redirect, authentication and
session management weaknesses. You understand root causes, not just names.
Web and Browser Fundamentals - Solid understanding of how web applications work:
HTTP request/response cycle, client-server model, REST APIs, how browsers handle
same-origin policy, cookies and their attributes, and CORS. This is the foundation
everything else builds on.
Security Testing Tools - Hands-on experience with Burp Suite or similar web
application security testing tools. You have used them to intercept, modify, and replay
requests - not just run automated scans.
Vulnerability Documentation - Able to reproduce a vulnerability and write it up clearly:
reproduction steps, proof of concept, and impact statement. Findings that engineering
teams cannot reproduce or understand do not get fixed.
Secure Development Awareness - Familiarity with foundational secure coding
concepts: input validation, output encoding, parameterized queries, and least privilege.
Code Readability - Ability to read and follow code in at least one language relevant to
web security - PHP, Python, JavaScript, or Go. You don't need to be a developer, but you
need to follow logic and spot security-relevant patterns.
Analytical Thinking - You reason through problems methodically. You can explain not
just what a vulnerability is but why it exists, how it is exploited, and what fixing it
actually requires.
Clear Written Communication - You write findings and summaries that are precise,
reproducible, and useful to the engineers who need to act on them.
Curiosity and Initiative - You dig into problems rather than stopping at the surface.
When something looks wrong, you investigate before concluding.
Nice to Have
Participation in bug bounty programs or CTF competitions Basic scripting ability for automation - Python or Bash
Familiarity with CI/CD pipelines and where security tooling fits
Exposure to cloud environments - GCP, AWS, or Azure
Relevant coursework or certifications - eWPT, CEH, or similar entry-level credentials
