LiveActive security incident?Get immediate response
CVE Record

CVE-2021-47211: ALSA: usb-audio: fix null pointer dereference on pointer cs_desc

In the Linux kernel, the following vulnerability has been resolved: ALSA: usb-audio: fix null pointer dereference on pointer cs_desc The pointer cs_desc return from snd_usb_find_clock_source could be null, so there is a potential null pointer dereference issue. Fix this by adding a null check before dereference.

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47211 is a Linux kernel bug in ALSA USB audio handling. A missing null check could let the kernel dereference a missing clock-source descriptor, likely causing a crash or denial of service. The source bundle does not provide CVSS, CWE, exploit evidence, or distribution-specific impact.

Executive priority

Treat this as a hygiene and availability risk, not an emergency, unless high-value systems accept untrusted USB devices. Prioritize normal kernel patching and confirm vendor coverage because severity and exploit evidence are incomplete.

Technical view

The resolved issue adds a null check before dereferencing cs_desc returned by snd_usb_find_clock_source. The affected component is Linux ALSA usb-audio. Available evidence describes a potential null pointer dereference, but does not specify attack prerequisites, privilege requirements, or reliable impact beyond kernel fault risk.

Likely exposure

Exposure is most relevant to Linux systems using affected kernel builds with USB audio support. Practical exposure likely depends on whether USB audio devices can be attached or presented to the host. Distribution backport status must be checked separately.

Exploitation context

The bundle does not show KEV listing, active exploitation, public exploit details, or weaponization evidence. Based on the description, the plausible impact is local or device-mediated denial of service, but prerequisites are not fully documented in the provided sources.

Researcher notes

Official data identifies a null pointer dereference fixed in Linux stable commits. The bundle lacks CVSS, CWE, exploitability analysis, and distro-specific fixed versions. Avoid assuming remote reachability or code execution from the provided evidence.

Mitigation direction

  • Update to a vendor-supported kernel containing the referenced stable fixes.
  • Check Linux distribution advisories for backported fixes and affected package versions.
  • Restrict untrusted physical or virtual USB device attachment where feasible.
  • Disable unused USB audio support only if operationally acceptable.
  • Track vendor guidance because no separate workaround is named in the bundle.

Validation and detection

  • Inventory Linux kernel versions across endpoints, servers, and appliances.
  • Confirm whether USB audio support is enabled or loadable.
  • Map installed distribution kernel packages to vendor fixed builds.
  • Review change logs for the referenced ALSA usb-audio null-check fix.
  • Verify exposure assumptions for systems accepting user-controlled USB devices.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2021-47211 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux1dc669fed61a4ec4270a89e5fb3535802cc45668, 1dc669fed61a4ec4270a89e5fb3535802cc45668, 1dc669fed61a4ec4270a89e5fb3535802cc45668unaffected
LinuxLinux3.10, 0, 5.10.259, 5.15.5, 5.16affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.