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CVE Record

CVE-2021-46924: NFC: st21nfca: Fix memory leak in device probe and remove

In the Linux kernel, the following vulnerability has been resolved: NFC: st21nfca: Fix memory leak in device probe and remove 'phy->pending_skb' is alloced when device probe, but forgot to free in the error handling path and remove path, this cause memory leak as follows: unreferenced object 0xffff88800bc06800 (size 512): comm "8", pid 11775, jiffies 4295159829 (age 9.032s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000d66c09ce>] __kmalloc_node_track_caller+0x1ed/0x450 [<00000000c93382b3>] kmalloc_reserve+0x37/0xd0 [<000000005fea522c>] __alloc_skb+0x124/0x380 [<0000000019f29f9a>] st21nfca_hci_i2c_probe+0x170/0x8f2 Fix it by freeing 'pending_skb' in error and remove.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This CVE is a Linux kernel memory leak in the ST21NFCA NFC driver. During device setup or removal, an allocated network buffer was not freed. The likely business impact is local system resource loss on systems using this NFC hardware, not a broad remote compromise scenario based on the provided sources.

Executive priority

Treat as a low-priority kernel hygiene fix unless affected NFC-capable systems are mission critical or repeatedly probing/removing devices. Fold remediation into normal kernel patch cycles, with faster action for exposed embedded or kiosk fleets using NFC.

Technical view

The vulnerable code is in the Linux kernel NFC st21nfca HCI I2C driver. phy->pending_skb is allocated during probe, but was not freed on probe error paths or device removal. Stable kernel commits fix this by freeing pending_skb in those paths.

Likely exposure

Exposure is likely limited to Linux systems with the ST21NFCA NFC driver and relevant NFC/I2C hardware or enabled module. The source bundle lists affected Linux kernel versions and stable fixes, but does not provide distribution-specific package status.

Exploitation context

The provided sources do not show active exploitation, public exploit availability, KEV listing, or a remote attack path. The issue is described as a memory leak during probe and remove handling, so availability degradation is the clearest concern from the evidence.

Researcher notes

Evidence supports a kernel memory leak, not code execution. The source bundle lacks CVSS, CWE, distribution impact, exploitability analysis, and trigger prerequisites beyond probe/remove paths. Validate reachability through driver configuration and hardware presence before escalating.

Mitigation direction

  • Check whether systems load or build the st21nfca NFC driver.
  • Update to a kernel containing the referenced stable fix commits.
  • Review Linux distribution advisories for patched package versions.
  • Disable unused NFC functionality where operationally acceptable.

Validation and detection

  • Inventory kernel versions across Linux assets.
  • Check whether ST21NFCA NFC hardware or modules are present.
  • Confirm vendor kernel packages include the stable fix commits.
  • Review logs or diagnostics for repeated probe failures or NFC device churn.
Prepared
Confidence
medium
Sources
8

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-2021-46924 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
7Source 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
LinuxLinux68957303f44a501af5cf37913208a2acaa6bcdf1, 68957303f44a501af5cf37913208a2acaa6bcdf1, 68957303f44a501af5cf37913208a2acaa6bcdf1, 68957303f44a501af5cf37913208a2acaa6bcdf1, 68957303f44a501af5cf37913208a2acaa6bcdf1, 68957303f44a501af5cf37913208a2acaa6bcdf1unaffected
LinuxLinux3.16, 0, 4.14.261, 4.19.224, 5.4.170, 5.10.90, 5.15.13, 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.