CVE-2021-35093
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 · uneditedPossible memory corruption in BT controller when it receives an oversized LMP packet over 2-DH1 link and leads to denial of service in BlueCore
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 memory corruption vulnerability exists in the BlueCore Bluetooth controller firmware. The issue occurs when the controller processes an oversized Link Management Protocol (LMP) packet received over a 2-DH1 data link, causing memory corruption that leads to denial of service.
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 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 controller hardwareOn Linux, run 'hciconfig -a' or 'bluetoothctl list' to see the controller name and manufacturer. On Windows, check Device Manager under Bluetooth radios. Look for identifiers containing 'CSR8510' or 'CSR8811' or 'Qualcomm' or 'CSR'.Affected if The controller is a Qualcomm Csr8510 or Csr8811 chipset
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Check the Bluetooth controller firmware versionUse 'hcitool -V' or 'hciconfig -v' to read firmware version. On Windows, check the Bluetooth driver properties. For CSR chips, you may need vendor-specific tools like CSR BlueSuite or bccmd.Affected if The firmware version matches Csr8510 A10 or Csr8811 A12 (or if the firmware cannot be determined or updated)
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Monitor for active 2-DH1 data linksUse monitoring tools like 'btmon' or Wireshark with Bluetooth sniffing to observe ACL connections. 2-DH1 is an enhanced data rate (EDR) packet type. Check connection logs or use 'hcitool con' to list active connections.Affected if 2-DH1 data links are established between the controller and remote devices
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Check for Bluetooth controller crash logs or instabilityReview system logs (dmesg, Event Viewer on Windows) for Bluetooth controller errors, crashes, or memory corruption indicators since the last update. Look for unexpected disconnections or failure to pair.Affected if The controller exhibits unexplained crashes, memory errors, or failure to respond after receiving LMP packets from a remote device
You are affected if your system uses a Qualcomm Csr8510 or Csr8811 Bluetooth controller with the vulnerable firmware and 2-DH1 data links can be established between devices.
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 vendor firmware updates from Qualcomm/CSR for affected BlueCore chipsets. As a workaround, consider disabling Bluetooth or restricting to safer link configurations until patching is possible.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-35093 — 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-2021-35093 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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- Version or environment caveats, and links to real fixes
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