CVE-2021-1956
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 · uneditedImproper handling of ASB-U packet with L2CAP channel ID by slave host can lead to interference with piconet in Snapdragon Auto, Snapdragon Compute, Snapdragon Connectivity, Snapdragon Consumer Electronics Connectivity, Snapdragon Industrial IOT, Snapdragon Mobile, Snapdragon Voice & Music
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 confidenceThis is a Bluetooth stack vulnerability in Qualcomm Snapdragon chipsets where improper handling of ASB-U packets with L2CAP channel IDs by a slave host can cause interference with the piconet (Bluetooth personal area network). The vulnerability allows a remote attacker to potentially disrupt Bluetooth communications by sending specially crafted ASB-U packets.
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
- 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 Bluetooth chipset modelDetermine the Qualcomm chipset used for Bluetooth in the device (e.g., check system info, Bluetooth adapter details, or device specifications)Affected if The chipset is one of: Aqt1000, Ar8035, Csrb31024, Qca6175a, Qca6390, Qca6391, Qca6420, or Qca6430
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Check the Bluetooth firmware versionQuery the Bluetooth firmware version through the device's system settings, Bluetooth stack diagnostics, or vendor-specific toolsAffected if Any firmware version is installed on the affected chipsets (all versions are vulnerable)
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Verify Bluetooth is enabledConfirm that Bluetooth functionality is turned on in the device settingsAffected if Bluetooth is active and the device uses an affected Qualcomm chipset
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Confirm device role as Bluetooth slaveObserve whether the device connects to other Bluetooth devices as a slave (secondary) in a piconet configurationAffected if The device operates as a Bluetooth slave and uses an affected Qualcomm chipset with Bluetooth enabled
If the device contains any of the listed Qualcomm Bluetooth chipsets (Aqt1000, Ar8035, Csrb31024, Qca6175a, Qca6390, Qca6391, Qca6420, Qca6430) with Bluetooth enabled, it is potentially affected by this vulnerability when acting as a slave host.
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 firmware updates provided by device OEMs that include the Qualcomm Bluetooth stack patch for this vulnerability. Users should check with their device manufacturers for available updates.
- Consultation4.0 h
- Testing8.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,776.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1956 — 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-2021-1956 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
- No weaponised exploit code, or anything meant to cause harm
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