CVE-2025-8821
📋 TL;DR
This CVE describes a command injection vulnerability in Linksys range extender firmware that allows remote attackers to execute arbitrary operating system commands by manipulating the bssid parameter. The vulnerability affects multiple Linksys RE series models up to August 1, 2025. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Linksys RE6250
- Linksys RE6300
- Linksys RE6350
- Linksys RE6500
- Linksys RE7000
- Linksys RE9000
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing persistent backdoor installation, network pivoting to internal systems, and data exfiltration.
Likely Case
Device takeover for botnet recruitment, credential harvesting from connected devices, or network disruption.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Proof-of-concept exploit is publicly available on GitHub, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: No
Instructions:
No official patch available. Check Linksys support website regularly for firmware updates addressing CVE-2025-8821.
🔧 Temporary Workarounds
Network Segmentation
allIsolate Linksys range extenders on separate VLANs with strict firewall rules preventing external access to management interfaces.
Access Control
allImplement network access control lists to restrict access to the vulnerable /goform/RP_setBasic endpoint.
🧯 If You Can't Patch
- Disable remote management features on affected devices
- Replace vulnerable devices with patched alternatives if available
🔍 How to Verify
Check if Vulnerable:
Check device firmware version via web interface (typically under Administration > Firmware Update) and verify if it's dated before August 1, 2025.Check Version:
No CLI command available. Use web interface: http://[device-ip]/FirmwareUpdate.htmVerify Fix Applied:
Verify firmware version is newer than 20250801 or check vendor advisory for specific patched version.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/RP_setBasic with shell metacharacters in bssid parameter
- Unexpected process execution from web server context
Network Indicators:
- HTTP requests containing shell commands in URL parameters
- Outbound connections from range extenders to suspicious external IPs
SIEM Query:
source="linksys-extender" AND (url="/goform/RP_setBasic" AND (param="bssid" AND value MATCHES "[;&|`$()]"))🔗 References
- https://github.com/wudipjq/my_vuln/blob/main/Linksys1/vuln_55/55.md
- https://github.com/wudipjq/my_vuln/blob/main/Linksys1/vuln_55/55.md#poc
- https://vuldb.com/?ctiid.319355
- https://vuldb.com/?id.319355
- https://vuldb.com/?submit.626685
- https://www.linksys.com/
- https://github.com/wudipjq/my_vuln/blob/main/Linksys1/vuln_55/55.md
- https://github.com/wudipjq/my_vuln/blob/main/Linksys1/vuln_55/55.md#poc
