H3C Magic B3 Vulnerability (CVE-2026-8764) Exposes Routers to Remote Buffer Overflow
The National Vulnerability Database (NVD) has disclosed CVE-2026-8764, a critical buffer overflow vulnerability impacting H3C Magic B3 routers up to version 100R002. This flaw resides within the UpdateWanParams function of the /goform/aspForm file, where improper handling of the param argument can lead to remote code execution.
Rated with a CVSS score of 7.2 (HIGH), this vulnerability is remotely exploitable without user interaction, requiring only high privileges on the device. The exploit has been publicly disclosed, significantly increasing the risk of widespread attacks. The National Vulnerability Database notes that H3C was contacted about the disclosure but did not respond.
This is a serious concern for any organization or individual relying on these devices. Publicly available exploits mean attackers don’t need to spend time on initial research; they can go straight to weaponization. The implications are severe: full compromise of a router can lead to network segmentation bypass, traffic interception, or the establishment of persistent backdoors within a target network.
What This Means For You
- If your organization or home network utilizes H3C Magic B3 routers, you are at high risk. Given the public exploit and lack of vendor response, these devices are a prime target. Immediately isolate these routers, or if replacement is not feasible, implement strict network segmentation to minimize potential lateral movement if a device is compromised. Monitor network traffic for any anomalous activity originating from or destined for these routers.
Related ATT&CK Techniques
🛡️ Detection Rules
2 rules · 6 SIEM formats2 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-8764 H3C Magic B3 UpdateWanParams Buffer Overflow
title: CVE-2026-8764 H3C Magic B3 UpdateWanParams Buffer Overflow
id: scw-2026-05-17-ai-1
status: experimental
level: critical
description: |
Detects attempts to exploit CVE-2026-8764 by targeting the UpdateWanParams function within the /goform/aspForm endpoint on H3C Magic B3 devices. This rule specifically looks for POST requests to '/goform/aspForm' containing 'UpdateWanParams' in the query string, indicating a potential buffer overflow attempt.
author: SCW Feed Engine (AI-generated)
date: 2026-05-17
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-8764/
tags:
- attack.initial_access
- attack.t1190
logsource:
category: webserver
detection:
selection:
cs-uri|contains:
- '/goform/aspForm'
cs-uri-query|contains:
- 'UpdateWanParams'
cs-method|exact:
- 'POST'
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-8764 | Buffer Overflow | H3C Magic B3 up to 100R002 |
| CVE-2026-8764 | Buffer Overflow | Vulnerable function: UpdateWanParams in /goform/aspForm |
| CVE-2026-8764 | Buffer Overflow | Manipulation of argument 'param' |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 18, 2026 at 01:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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