CVE-2021-30307
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 denial of service due to improper validation of DNS response when DNS client requests with PTR, NAPTR or SRV query type in Snapdragon Auto, Snapdragon Compute, Snapdragon Connectivity, Snapdragon Consumer IOT, Snapdragon Industrial IOT
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 denial-of-service vulnerability exists in the DNS client component of Qualcomm Snapdragon chipsets due to improper validation of DNS responses. The vulnerability specifically affects PTR, NAPTR, and SRV query types, allowing malformed or malicious DNS responses to cause the DNS client to fail or behave unexpectedly.
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 chipset model in useCheck system information, device specifications, or network interface hardware details to determine if a Qualcomm Snapdragon chipset (Ar8035, Csrb31024, Qca6174a, Qca6390, Qca6391, Qca6426, Qca6436, Qca6564au) is present. This may be found in /proc/cpuinfo, device manager, or product documentation.Affected if The system uses any of the listed Qualcomm chipset models (Ar8035, Csrb31024, Qca6174a, Qca6390, Qca6391, Qca6426, Qca6436, Qca6564au).
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Determine the installed firmware versionAccess the firmware version through the device management interface, bootloader information, or by querying the chipset firmware directly if accessible (e.g., via AT commands for modems, or system logs during boot).Affected if The firmware version cannot be determined to be patched, or the device uses the affected firmware without an available update.
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Confirm DNS client functionality is enabledVerify that the DNS client component is actively used on the device. Check network configuration files, DNS resolver settings (e.g., /etc/resolv.conf on Linux, or network stack configuration on embedded systems), and verify the device performs DNS queries.Affected if The device uses its own DNS client to resolve queries, particularly for PTR, NAPTR, or SRV record types.
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Check if PTR, NAPTR, or SRV queries are performedMonitor network traffic or review DNS query logs to determine if the device or its DNS client performs reverse DNS (PTR), Naming Authority Pointer (NAPTR), or Service (SRV) record queries.Affected if The device performs any PTR, NAPTR, or SRV DNS queries, as these are the specific query types vulnerable to malformed response handling.
The environment is affected if it uses any of the listed Qualcomm chipsets (Ar8035, Csrb31024, Qca6174a, Qca6390, Qca6391, Qca6426, Qca6436, Qca6564au) with the vulnerable DNS client functionality and performs PTR, NAPTR, or SRV queries.
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 Qualcomm firmware/security updates for affected Snapdragon Auto, Compute, Connectivity, Consumer IOT, and Industrial IOT chipsets. For embedded systems, verify DNS response handling and consider network-level DNS filtering as a compensating control until firmware updates are available.
- Consultation6.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-30307 — 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-2021-30307 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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