Stack-based Buffer Overflow in FiberHome AN5506-04-FA Firmware
CVE-2021-4464

9.3CRITICAL

Key Information:

Vendor

Fiberhome

Status
An5506-04-fa
Hg6245d
Vendor
CVE Published:
12 November 2025

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2021-4464?

The firmware of FiberHome's AN5506-04-FA and HG6245D products is susceptible to a stack-based buffer overflow due to inadequate validation of Cookie header lengths. Specifically, when the HTTP service processes a Cookie exceeding 511 bytes, it leads to a stack buffer overrun. This vulnerability may cause device crashes or allow attackers to manipulate execution flow, compromising the security and functionality of affected devices. Users are advised to upgrade to the latest firmware versions to mitigate this risk.

Affected Version(s)

AN5506-04-FA 0

HG6245D 0

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2021-4464 - Proof of Concept

CVE-2021-4464 - Proof of Concept

References

https://pierrekim.github.io/blog/2021-01-12-fiberhome-ont...
technical-descriptionexploit
https://pierrekim.github.io/advisories/2021-fiberhome-0x0...
technical-descriptionexploit
https://www.vulncheck.com/advisories/fiberhome-routers-re...
third-party-advisory

CVSS V4

Score:
9.3
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Pierre Barre
JSON
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CVE-2021-4464 : Stack-based Buffer Overflow in FiberHome AN5506-04-FA Firmware