CVE-2021-30340
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 · uneditedReachable assertion due to improper validation of coreset in PDCCH configuration in SA mode in Snapdragon Auto, Snapdragon Compute, Snapdragon Connectivity, Snapdragon Industrial IOT, Snapdragon Mobile
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 reachable assertion vulnerability exists in the PDCCH (Physical Downlink Control Channel) configuration handling for Standalone (SA) mode in Qualcomm Snapdragon chipsets. The coreset validation is improper, allowing an attacker to trigger a reachable assertion that could cause a 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 versionsall 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/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 chipset modelUse `lspci | grep -i network` or check `/proc/device-tree/model` or `cat /sys/firmware/devicetree/base/model` to identify the Qualcomm Snapdragon chipsetAffected if The chipset model matches one of: Ar8035, Qca6390, Qca6391, Qca6426, Qca6436, Qca6574a, Qca6574au, Qca6595au
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Check firmware versionRun `dmesg | grep -i firmware` or use vendor tools like `iw dev` to retrieve the installed Wi-Fi/cellular firmware versionAffected if The firmware version corresponds to any of the listed affected chipset models (all versions are affected)
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Verify Standalone (SA) mode is enabledCheck cellular modem configuration via `at+cgdcont` or equivalent AT command, or check network interface configuration for 5G SA mode statusAffected if The device is configured to use 5G Standalone (SA) mode rather than Non-Standalone (NSA) mode
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Inspect PDCCH configurationUse cellular modem diagnostic tools or vendor-specific AT commands to query the Physical Downlink Control Channel (PDCCH) coreset configuration parametersAffected if The coreset validation is present and improperly configured, potentially triggering a reachable assertion
You are affected if your device uses any of the listed Qualcomm chipset models (Ar8035, Qca6390, Qca6391, Qca6426, Qca6436, Qca6574a, Qca6574au, Qca6595au) with firmware that supports 5G Standalone mode, as all versions of these chipsets are vulnerable.
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-provided firmware/security patch from Qualcomm to affected Snapdragon chipset implementations. OEM device manufacturers should integrate the patch and distribute via carrier/OTA updates.
- Consultation8.0 h
- Implementation40.0 h
- Testing60.0 h
- Review / QA16.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $33,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-30340 — 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-2021-30340 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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