CVE-2025-50399Public exploitNetwork attack vector

Router crash via unchecked password length

Published Nov 26, 2025 · Updated Dec 4, 2025

Buffer overflow in FAST FAC1200R firmware F400_FAC1200R_Q allows remote attackers to crash the router via a crafted HTTP password value. The sub_80435780 function handles the password string without checking its length, so an oversized value overflows the destination buffer. Network reachability to the HTTP management interface is required, and the demonstrated consequence is a device crash rather than persistent damage.

CVSS severity9.8
Critical
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Buffer overflow in FAST FAC1200R firmware F400_FAC1200R_Q allows remote attackers to crash the router via a crafted HTTP password value. The sub_80435780 function handles the password string without checking its length, so an oversized value overflows the destination buffer. Network reachability to the HTTP management interface is required, and the demonstrated consequence is a device crash rather than persistent damage.

The record

CVE
CVE-2025-50399
Published
Nov 26, 2025
Updated
Dec 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 26, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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