Vulnerability · Published Nov 12, 2025 · Assigned by VulnCheck

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

Critical 9.3

In plain English

A critical-severity stack buffer overflow in AN5506-04-FA from FiberHome. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.2% (higher than 82% of all known vulnerabilities).

Severity (CVSS 4.0)9.3Critical

Exploit odds (30 days)2.2%top 17.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 (as reported)

Vendor	Product	Versions
FiberHome	AN5506-04-FA	0 – through RP2631
FiberHome	HG6245D	0 – before RP2602

Weakness: CWE-121 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References

https://pierrekim.github.io/blog/2021-01-12-fiberhome-ont-0day-vulnerabilities.html#misc-remote-stack-overflow-an5506 technical-description, exploit
https://pierrekim.github.io/advisories/2021-fiberhome-0x00-ont.txt technical-description, exploit
https://www.vulncheck.com/advisories/fiberhome-routers-remote-stack-overflow third-party-advisory