CVE-2026-101039
Received Received - Intake

Stack-Based Buffer Overflow in FAST FAC1900R Device

Publication date: 2026-09-28

Last updated on: 2026-09-28

Assigner: VulDB

Description
A vulnerability was identified in FAST FAC1900R 20190827_2.0.2. Affected by this issue is the function copy_msg_element of the component devdiscover Service. Such manipulation leads to stack-based buffer overflow. The attack can be executed remotely. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.

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Meta Information

Published
2026-09-28
Last Modified
2026-09-28
Generated
2026-09-28
AI Q&A
2026-09-28
EPSS Evaluated
N/A
NVD
CVE-2026-101039
EUVD
EUVD-2026-88211

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
fast fac1900r 20190827_2.0.2
fast fabric1900r 20190827_2.0.2

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-121 A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
CWE-119 The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

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Executive Summary

This is a stack-based buffer overflow vulnerability in the FAST FAC1900R router firmware version 20190827_2.0.2. It exists in the copy_msg_element function of the devdiscover service, which handles LAN device discovery on UDP port 5001. The function does not validate a user-controlled length field before using it in a memcpy operation, allowing attackers to overwrite stack memory including the return address. This can cause service crashes or enable control-flow hijacking.

Detection Guidance

To detect this vulnerability, scan your network for devices running the vulnerable FAST FAC1900R firmware version 20190827_2.0.2. Check for open UDP port 5001, which is used by the devdiscover service. Use network scanning tools like nmap to identify devices with this port open. Example command: nmap -sU -p 5001 <target_IP>. If the service responds, further analysis may be needed to confirm the vulnerable function.

Impact Analysis

An attacker could exploit this by sending a specially crafted UDP packet to port 5001, triggering a buffer overflow. This may lead to remote code execution, service crashes, or unauthorized access to the router. Since the exploit is publicly available, the risk of attack is higher. The vendor has not provided a patch, so mitigation relies on workarounds like adding bounds checks or using safer functions.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches, violating confidentiality requirements in GDPR and HIPAA. Remote code execution risks may also compromise data integrity and availability. Organizations using affected devices must implement compensating controls or isolate systems to maintain compliance until a patch is available.

Mitigation Strategies

Immediately restrict access to UDP port 5001 on affected devices by blocking it at the firewall level. Isolate vulnerable devices from critical network segments. Monitor network traffic for unusual activity on this port. If possible, implement application-layer filtering to validate packet lengths before processing. Since no official patch exists, consider replacing the device or contacting the vendor for a potential workaround.

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