CVE-2025-7921
📋 TL;DR
This critical vulnerability affects certain Askey modem models, allowing unauthenticated remote attackers to exploit a stack-based buffer overflow to execute arbitrary code. The vulnerability is remotely exploitable without authentication, affecting devices exposed to the internet or internal networks.
💻 Affected Systems
- Askey modem models (specific models not detailed in provided references)
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the modem allowing attackers to execute arbitrary code, pivot to internal networks, intercept/modify traffic, and establish persistent backdoors.
Likely Case
Remote code execution leading to device takeover, network traffic interception, and potential lateral movement to connected devices.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
The vulnerability is unauthenticated and stack-based buffer overflows are typically straightforward to exploit once details are known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in provided references
Vendor Advisory: https://www.twcert.org.tw/en/cp-139-10269-c9839-2.html
Restart Required: Yes
Instructions:
1. Check Askey website for firmware updates. 2. Download latest firmware for your modem model. 3. Access modem admin interface. 4. Navigate to firmware update section. 5. Upload and apply new firmware. 6. Reboot modem.
🔧 Temporary Workarounds
Network Segmentation
allPlace modems in isolated network segments with strict firewall rules
Access Control Lists
allImplement strict inbound firewall rules to limit access to modem management interfaces
🧯 If You Can't Patch
- Replace affected modems with non-vulnerable models
- Implement strict network segmentation and firewall rules to isolate modems from critical networks
🔍 How to Verify
Check if Vulnerable:
Check modem model and firmware version against Askey's vulnerability list. Access modem admin interface and note model/firmware details.Check Version:
Access modem web interface (typically http://192.168.1.1) and navigate to status/system information pageVerify Fix Applied:
Verify firmware version has been updated to patched version. Check Askey's advisory for specific fixed version numbers.📡 Detection & Monitoring
Log Indicators:
- Unusual traffic patterns to modem management ports
- Multiple failed connection attempts followed by successful exploit
- Modem reboot logs without user action
Network Indicators:
- Unusual outbound connections from modem
- Traffic patterns indicating command and control communication
- Port scanning activity targeting modem management ports
SIEM Query:
source_ip=external AND dest_ip=modem_ip AND dest_port IN (80,443,8080,8443) AND bytes_sent>threshold