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CVE Record

CVE-2021-47306: net: fddi: fix UAF in fza_probe

In the Linux kernel, the following vulnerability has been resolved: net: fddi: fix UAF in fza_probe fp is netdev private data and it cannot be used after free_netdev() call. Using fp after free_netdev() can cause UAF bug. Fix it by moving free_netdev() after error message. TURBOchannel adapter")

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-47306 is a Linux kernel use-after-free flaw in the FDDI fza driver probe path. The available sources describe a fixed coding error after free_netdev(), but do not provide CVSS, exploitability, or impact details. Exposure appears limited to systems using or building this legacy network driver path.

Executive priority

Handle through normal kernel patch governance unless your environment uses the affected legacy FDDI driver. Escalate priority for specialized systems where this driver is present, because kernel use-after-free flaws can have serious reliability or security consequences.

Technical view

The bug is in fza_probe: fp points to netdev private data and was used after free_netdev(). Linux fixed this by moving free_netdev() after the error message. This is kernel memory-safety behavior in an error path, but the source bundle does not describe a reachable exploit primitive or affected configuration details.

Likely exposure

Most exposure is likely niche: Linux systems with the FDDI fza TURBOchannel adapter driver present and reachable. The CVE data lists Linux as affected across several kernel version entries, but does not provide complete distribution package mapping.

Exploitation context

CISA KEV is false, and the provided sources do not report active exploitation, public weaponization, or attacker prerequisites. Treat it as a kernel memory-safety issue requiring environment-specific validation rather than an internet-scale emergency.

Researcher notes

Evidence is limited to the Linux kernel fix description and stable commit references. No CVSS, CWE, exploit status, or complete downstream version mapping is provided. The key validation question is whether fza_probe is reachable in the target kernel and hardware configuration.

Mitigation direction

  • Check vendor or distribution advisories for the fixed kernel package.
  • Prioritize updates on systems enabling the fza FDDI driver.
  • Disable or remove unused legacy FDDI driver support where operationally safe.
  • Track the referenced stable kernel commits during patch verification.

Validation and detection

  • Inventory Linux kernel versions against vendor advisory status.
  • Check whether the fza FDDI driver is built, packaged, or loadable.
  • Confirm fixed kernel commits or downstream backports are present.
  • Review asset exposure for legacy TURBOchannel or FDDI hardware dependencies.
Prepared
Confidence
medium
Sources
6

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

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CVE-2021-47306 mapping review

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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
5Source 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
LinuxLinux61414f5ec9834df8aa4f55c90de16b71a3d6ca8d, 61414f5ec9834df8aa4f55c90de16b71a3d6ca8d, 61414f5ec9834df8aa4f55c90de16b71a3d6ca8d, 61414f5ec9834df8aa4f55c90de16b71a3d6ca8dunaffected
LinuxLinux4.20, 0, 5.4.135, 5.10.53, 5.13.5, 5.14affected
Weakness

CWE details

No CWE listed

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