CVE-2021-35076
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 null pointer dereference due to improper validation of RRC connection reconfiguration message 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 null pointer dereference vulnerability exists in the RRC (Radio Resource Control) connection reconfiguration message handling within Qualcomm Snapdragon baseband/modem firmware. Improper validation of specially crafted RRC messages can lead to a null pointer dereference, potentially causing denial of service or enabling further exploitation. The vulnerability affects multiple Snapdragon product lines including Auto, Compute, Connectivity, Industrial IOT, and Mobile chipsets.
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 the Qualcomm chipset in useCheck the device hardware specifications, modem firmware details, or system information to determine if the device contains one of the affected chipsets: Ar8035, Qca6390, Qca6391, Qca6421, Qca6426, Qca6431, Qca6436, or Qca6574a. On Linux systems, this may appear in lspci, lsusb, or kernel logs. On mobile devices, check About Phone or baseband/modem information in settings.Affected if The device uses any of the listed Qualcomm chipset models (Ar8035, Qca6390, Qca6391, Qca6421, Qca6426, Qca6431, Qca6436, or Qca6574a)
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Retrieve baseband/modem firmware versionQuery the modem firmware version through available diagnostic interfaces. On mobile devices, check Settings > About Phone > Baseband or modem version. On embedded devices, use AT commands such as 'AT+CGMR' or 'AT+QFWVER' (varies by module). On Linux, check /proc/cpuinfo or network interface driver information for firmware version strings.Affected if The installed firmware version matches one of the affected chipset families listed in the CVE (all versions of these specific chipsets are affected)
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Confirm RRC message handling is activeRRC (Radio Resource Control) is a core protocol in LTE/5G baseband processing and is typically always active when the modem has a cellular connection. Verify the device has an active cellular or wireless modem interface (for Wi-Fi chipsets like QCA series). Check if the network interface is present and operational using ip link or similar tools.Affected if The device has an active cellular or wireless modem connection using the affected Qualcomm chipset, meaning RRC message processing is occurring in the baseband firmware
A device is affected if it contains any of the listed Qualcomm chipsets (Ar8035, Qca6390, Qca6391, Qca6421, Qca6426, Qca6431, Qca6436, or Qca6574a) and has an active cellular or wireless connection where RRC messages are processed by the baseband firmware.
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-supplied firmware updates from Qualcomm through device manufacturer channels. Since this is a baseband firmware vulnerability, end users cannot directly patch it and must wait for device manufacturer updates. Prioritize updating mobile devices and IoT equipment operating in sensitive environments.
- Consultation8.0 h
- Implementation4.0 h
- Testing12.0 h
- Review / QA6.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-35076 — 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-2021-35076 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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