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Ar8035 FirmwareOperating system · Qualcomm

CVE-2021-35096

HIGH · 7.5 CVSS v3.1 Published 2022-06-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
Improper memory allocation during counter check DLM handling can lead to denial of service 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 confidence

A memory allocation flaw exists in the counter check logic of the DLM (Data Link Manager) subsystem in Qualcomm Snapdragon chipsets. During counter validation, improper memory allocation occurs which can cause the system to crash or become unresponsive, resulting in denial of service.

MitigationApply the vendor-provided firmware/security patch for CVE-2021-35096. Device manufacturers using affected Snapdragon variants should obtain and integrate the patch from Qualcomm and distribute via OTA updates.

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
Ar8035 FirmwareOperating system
Affected:all versions
Qca6390 FirmwareOperating system
Affected:all versions
Qca6391 FirmwareOperating system
Affected:all versions
Qca6421 FirmwareOperating system
Affected:all versions
Qca6426 FirmwareOperating system
Affected:all versions
Qca6431 FirmwareOperating system
Affected:all versions
Qca6436 FirmwareOperating system
Affected:all versions
Qca6574a FirmwareOperating system
Affected:all versions

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Qualcomm hardware in the system
    Examine system hardware information, device tree, or firmware tables (e.g., lspci, dmidecode, or boot logs) to list any Qualcomm Snapdragon network controllers, wireless adapters, or chipsets. Look specifically for devices using the Ar8035, Qca6390, Qca6391, Qca6421, Qca6426, Qca6431, Qca6436, or Qca6574a firmware.
    Affected if Any of the listed Qualcomm firmware variants (Ar8035, Qca6390, Qca6391, Qca6421, Qca6426, Qca6431, Qca6436, Qca6574a) are present in the system hardware or firmware enumeration.
  2. Check the installed firmware version
    Query the firmware version of the identified Qualcomm device using vendor-specific tools (e.g., ethtool -i, ath11k firmware loader, or chipset-specific diagnostic interfaces). Compare the firmware version string against the affected product list.
    Affected if The firmware version corresponds to any of the affected products (Ar8035, Qca6390, Qca6391, Qca6421, Qca6426, Qca6431, Qca6436, Qca6574a) since all versions of these products are vulnerable.
  3. Verify DLM subsystem is active
    Check if the Data Link Manager (DLM) subsystem is loaded or active on the Qualcomm device. This may involve checking kernel modules (e.g., lsmod for wireless drivers), device status, or firmware runtime state via debug interfaces if available.
    Affected if The DLM subsystem is initialized and running on the affected Qualcomm firmware, as the vulnerability exists in the counter check logic of DLM.
  4. Check for crash or denial of service indicators
    Review system logs (dmesg, kernel logs, firmware crash dumps) for unexplained system hangs, device resets, or memory allocation failures related to the network controller or DLM subsystem.
    Affected if The system exhibits unexplained crashes, hangs, or network subsystem failures consistent with the memory allocation flaw in DLM counter validation.

A system is affected if it contains any of the listed Qualcomm firmware products (Ar8035, Qca6390, Qca6391, Qca6421, Qca6426, Qca6431, Qca6436, Qca6574a) with the DLM subsystem active, as all versions of these products contain the memory allocation vulnerability in the DLM counter check logic.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-provided firmware/security patch for CVE-2021-35096. Device manufacturers using affected Snapdragon variants should obtain and integrate the patch from Qualcomm and distribute via OTA updates.

Fix this in Ar8035 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation24.0 h
  • Testing16.0 h
  • Review / QA8.0 h
56.0 hours of engineering $9,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-35096 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data