CVE-2021-31615
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 · uneditedUnencrypted Bluetooth Low Energy baseband links in Bluetooth Core Specifications 4.0 through 5.2 may permit an adjacent device to inject a crafted packet during the receive window of the listening device before the transmitting device initiates its packet transmission to achieve full MITM status without terminating the link. When applied against devices establishing or using encrypted links, crafted packets may be used to terminate an existing link, but will not compromise the confidentiality or integrity of the link.
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 confidenceUnencrypted BLE baseband links in Bluetooth Core Specifications 4.0-5.2 allow an adjacent attacker to inject crafted packets during the receive window before the transmitting device starts transmission, achieving MITM status without terminating the link. On encrypted links, the attack can only terminate connections but cannot compromise confidentiality or integrity.
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 data>= 4.0, <= 5.2CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:A/AC:H/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 Core Specification version in useConsult your device firmware/driver documentation, or check the Bluetooth stack version (e.g., via hci version command on Linux, or check the controller firmware version through manufacturer tools)Affected if The implementation uses Bluetooth Core Specification versions 4.0 through 5.2
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Determine if BLE links are encryptedInspect the BLE connection configuration or pairing settings. Check if LE Secure Connections (Secure Connections mode) is enabled in the BLE controller settings. On Linux, use btmon to monitor connection events and verify if encryption is active during connections.Affected if BLE connections are established without encryption (no LE Secure Connections or legacy BLE encryption)
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Verify the link encryption state during active BLE connectionsUse Bluetooth diagnostic tools (such as hcidump, btmon, or platform-specific BLE debug utilities) to capture connection events and verify the Encryption field in the connection parameters.Affected if Active BLE connections show encryption is disabled or not negotiated
Your environment is affected if your Bluetooth implementation conforms to Core Specification 4.0-5.2 and uses unencrypted BLE baseband links, allowing an adjacent attacker to achieve MITM status through packet injection during the receive window.
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 dataUse encrypted BLE connections (LE Secure Connections) where possible; implement application-layer authentication to add defense-in-depth; monitor for unexpected connection terminations that may indicate attack attempts.
- Consultation8.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-31615 — 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-2021-31615 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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