What’s Vulnerable › Vulnerabilities

CVE-2021-4464: FIberHome AN5506-04-FA / HG6245D Routers Remote Stack Overflow

• Severity: critical (CVSS 9.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-11-12 · updated 2026-06-17
• Weakness: CWE-121

Description

FiberHome AN5506-04-FA firmware versions up to and including RP2631 and HG6245D prior to RP2602 contain a stack-based buffer overflow, as the HTTP service ('webs') fails to enforce maximum lengths for Cookie header values. When a cookie longer than 511 bytes is processed, a stack buffer is overrun, leading to a crash or potential control of execution flow.

Affected products

• FiberHome AN5506-04-FA: through RP2631
• FiberHome HG6245D: before RP2602 — fixed in RP2602

How to fix

Upgrade to a fixed version: FiberHome HG6245D RP2602. Check the vendor advisory for mitigations.

References

• https://pierrekim.github.io/advisories/2021-fiberhome-0x00-ont.txt
• https://pierrekim.github.io/blog/2021-01-12-fiberhome-ont-0day-vulnerabilities.html#misc-remote-stack-overflow-an5506
• https://www.vulncheck.com/advisories/fiberhome-routers-remote-stack-overflow

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