CVE-2026-20405
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn Modem, there is a possible system crash due to a missing bounds check. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01688495; Issue ID: MSV-4818.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA missing bounds check in the Modem component allows a remote attacker controlling a rogue base station to cause a system crash on connected User Equipment (UE). The attacker does not need any additional privileges or user interaction to trigger this denial of service condition.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE dataall versionsall versionsall versionsall versionsCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify the modem hardware modelCheck the device hardware specifications or system information to determine if the modem is a Mediatek Nr15, Nr16, Nr17, or Nr17r variant. On Linux systems, this may appear in 'lspci', 'lsusb', or '/proc/cpuinfo' output, or within modem-specific AT command interfaces.Affected if The device uses a Mediatek Nr15, Nr16, Nr17, or Nr17r modem component
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Check the modem firmware versionQuery the modem firmware version through vendor-specific tools, AT commands (such as 'AT+CGMR' or 'AT+CGMM'), or system logs that contain modem initialization messages. Compare against the patch version MOLY01688495.Affected if The firmware version is earlier than MOLY01688495 or cannot be determined
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Verify cellular network connectivity is enabledCheck system configuration files or network settings to confirm whether the cellular modem is active and registered to a mobile network. Look for radio interface status in system network logs or through 'ip link' or 'nmcli' commands on Linux-based systems.Affected if Cellular/NR (5G) functionality is enabled and the device connects to base stations
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Check for rogue base station exposureReview mobile network connection logs for unexpected cell tower connections, or monitor for unusual base station identifiers (Cell IDs, LAC, TAC) that do not match expected network operator identifiers.Affected if The device has connected to or is susceptible to connecting to untrusted or unknown base stations
If the device contains a Mediatek Nr15/16/17/17r modem with firmware earlier than MOLY01688495 and has cellular connectivity enabled, the system is vulnerable to denial of service via rogue base station attacks.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply the vendor patch (MOLY01688495) to the affected modem firmware. Additionally, advise users to avoid connecting to untrusted or unknown base stations to reduce exposure to rogue cell tower attacks.
- Consultation4.0 h
- Implementation4.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-20405 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-20405 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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