GNU/Linux 6.1.0 (julio@portfolio) tty1

julio@portfolio:~$ whoami
>> JULIO CESAR
Full Stack Developer | AppSec | Pentester | Ethical Hacker

Full Stack Developer with solid experience in React and NodeJS. Worked in agile and international environments, building and scaling web/mobile solutions. Experienced in performance optimization, scalability, and integration of systems with robust APIs. I am also a Cybersecurity enthusiast, with a focus on vulnerability identification, ethical exploitation, and responsible disclosure. I have contributed to improving the security of major companies. I prioritize clear and assertive communication to enhance collaboration in agile teams.

julio@portfolio:~$ skills
Javascript
TypeScript
Ruby
React
Next.js
React Native
Tailwind
Node.js
Ruby on Rails
MongoDB
PostgreSQL
MySQL
Redis
Docker
AWS
Git
CI/CD
Jest
OWASP Top 10
Burp Suite
julio@portfolio:~$ experience
Full Stack Developer@Avantsoft// 2022 - 2024
  • >Architected scalable React web applications with reusable components, improving performance and accelerating delivery cycles across concurrent projects.
  • >Optimized NextJS applications for performance and SEO, enhancing page load speed and organic search visibility for client-facing platforms.
  • >Developed cross-platform mobile applications for iOS and Android using React Native, delivering consistent user experiences across devices
  • >Designed and developed RESTful APIs with Ruby on Rails and NodeJS, delivering well-structured and documented services that streamlined front-end integration.
  • >Managed concurrent projects for clients in e-commerce, agribusiness, and investment fund sectors, operating in agile and international environments.
// key projects:[Big Delivery][Big Delivery App][BMF][VCT Agro App]among other projects
julio@portfolio:~$ education
Bachelor in Software Engineering@UCSAL// 2022 - 2026
julio@portfolio:~$ vulnerabilities
Growth Supplements@Race Condition(CWE 367)
[critical]Fixed// 2025-09

> Endpoint /checkout/ajax/ajax-processar-venda.php exploited via single packet attack over HTTP/2. Firing multiple parallel requests over a single connection during checkout enabled double spending of gift card balance, where the same balance was consumed multiple times simultaneously, resulting in obtaining multiple gift cards at no additional cost.

// proofs:[#1][#2][#3]
Spoint@Race Condition(CWE 367)
[critical]Fixed// 2025-09

> Endpoint /crava/redeem-benefits exploited via single packet attack over HTTP/2. Firing multiple parallel requests over a single connection during welcome benefit redemption enabled double spending of the account's initial 50 points, where the same balance was consumed multiple times simultaneously, resulting in obtaining multiple R$5 credits at no additional point cost.

// proofs:[#1]
Justos@Race Condition(CWE 367)
[critical]Fixed// 2025-09

> Endpoint /rewards/redemption exploited via single packet attack over HTTP/2. Firing 20–30 parallel requests over a single connection during reward/voucher redemption enabled double spending of Justos points, where the same balance was consumed multiple times simultaneously. The exploitation resulted in a negative point balance on the account and the obtainment of multiple vouchers at no additional point cost.

// proofs:[#1][#2]
Zé Delivery@Race Condition(CWE 367)
[high]Fixed// 2026-02

> Endpoint /bff/consumers:accept-terms exploited via last-byte sync attack over HTTP/1.1. Firing 100+ synchronized parallel requests allowed multiple term acceptances on a single account, resulting in credit duplication in the "Zé Compensa" loyalty program.

// proofs:[#1][#2][#3]
Burger King@Lorem ipsum(CWE ???)
[critical]Reported// 2026-02

>

// in progress

Lorem ipsum@Mass Assignment / BOLA(CWE 915 / CWE 863)
[critical]Reported// 2026-02

>

// in progress

Vale Bonus@Lorem ipsum(CWE ???)
[critical]Acknowledged// 2025-09

>

// in progress

Soloist.ai (from Mozilla)@Lorem ipsum(CWE ???)
[high]Reported// 2026-02

>

// in progress

julio@portfolio:~$ contact
location:Salvador, Bahia - BR
julio@portfolio:~$