starrynightsecurity/cve-2025-54574-squid-heap-buffer-overflowVulnerability Found on Squid Proxy.
Vulnerability Found on Squid Proxy. CVE-2025-54574 — Critical Heap Buffer Overflow in Squid Proxy
This repository documents the discovery, analysis, and responsible disclosure process of CVE-2025-54574, a critical heap-based buffer overflow in Squid (<6.4) triggered during URN Trivial-HTTP response handling.
The vulnerability allowed an attacker-controlled server to cause out-of-bounds heap writes, memory corruption, and potential disclosure of up to 4KB of heap memory, including sensitive information.
📌 Severity: Critical (CVSS 9.8) 📌 Weakness: CWE-122 📌 Fixed in: Squid 6.4 📌 Discovered by: Guadalupe Colantonio (StarryNight)
🔍 Contents
/analysis/ → Technical explanation and memory analysis
/poc/ → Safe reproduction steps
/logs/ → Sanitized ASan & Valgrind outputs
README.md → Advisory summary
🧠 Summary of the Vulnerability
Due to improper buffer management in Squid’s URN processing subsystem, oversized responses could overflow a fixed-size heap buffer (~4096 bytes). This resulted in memory corruption and unintentional disclosure of heap content.
The bug affected all Squid versions up to 6.3, across multiple Linux distributions shipping outdated builds.
📅 Disclosure Timeline
2025-07-01 — Initial private report
2025-07-02 → 07-29 — Verification & maintainer coordination
2025-07-30 — CVE assigned
2025-07-31 — Advisory published
2025-08-xx — Patch included in Squid 6.4
📄 Official Advisory
GHSA-w4gv-vw3f-29g3 CVE-2025-54574
👤 Author
Guadalupe Colantonio — Security Researcher 🔗 GitHub: your username 📧 [email protected]
