CVE-2026-20405

7.5 HIGH
Denial of Service

📋 TL;DR

This vulnerability in MediaTek modems allows remote denial of service through system crashes when devices connect to rogue base stations. Attackers can trigger crashes without user interaction or special privileges. Affects devices using vulnerable MediaTek modem firmware.

💻 Affected Systems

Products:
  • MediaTek modem chipsets
Versions: Specific firmware versions not publicly disclosed in CVE description
Operating Systems: Android and other mobile OS using MediaTek modems
Default Config Vulnerable: ⚠️ Yes
Notes: Affects devices when connected to cellular networks. Exact chipset models not specified in CVE.

⚠️ Risk & Real-World Impact

🔴

Worst Case

Permanent device bricking requiring hardware replacement, complete loss of cellular connectivity, and potential cascading failures in cellular networks.

🟠

Likely Case

Temporary device crashes requiring reboots, intermittent loss of cellular service, and degraded network performance in affected areas.

🟢

If Mitigated

Isolated device crashes with automatic recovery, minimal service disruption when proper network segmentation and monitoring are in place.

🌐 Internet-Facing: HIGH
🏢 Internal Only: LOW

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ⚠️ Yes
Complexity: MEDIUM

Requires setting up rogue base station (IMSI catcher/stingray) which requires specialized equipment and knowledge.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Firmware with patch ID MOLY01688495

Vendor Advisory: https://corp.mediatek.com/product-security-bulletin/February-2026

Restart Required: Yes

Instructions:

1. Check device manufacturer for firmware updates. 2. Apply MediaTek modem firmware update containing patch MOLY01688495. 3. Reboot device after update.

🔧 Temporary Workarounds

Disable automatic network selection

all

Manually select trusted network operators to prevent connection to rogue base stations

Enable airplane mode in untrusted areas

all

Disable cellular radio when in locations where rogue base stations might operate

🧯 If You Can't Patch

  • Deploy cellular network monitoring to detect rogue base stations
  • Implement device management policies to restrict connections to untrusted networks

🔍 How to Verify

Check if Vulnerable:

Check modem firmware version against MediaTek security bulletin or contact device manufacturer

Check Version:

Device-specific commands vary by manufacturer (check *#*#4636#*#* on some Android devices)

Verify Fix Applied:

Verify modem firmware version contains patch ID MOLY01688495

📡 Detection & Monitoring

Log Indicators:

  • Unexpected modem resets
  • Frequent base station switching
  • Modem crash logs

Network Indicators:

  • Devices connecting to unexpected cell towers
  • Unusual signal strength patterns
  • Multiple devices crashing simultaneously in same area

SIEM Query:

source="modem_logs" AND (event="crash" OR event="reset") AND NOT reason="normal"

📊 Metadata

CVE ID: CVE-2026-20405
CVSS v3 Score: 7.5 (HIGH)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-617
Published: February 2, 2026
Last Updated: February 4, 2026

🤖 AI-assisted analysis, reviewed for accuracy

🔗 References

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