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CVE Record

CVE-2021-47171: net: usb: fix memory leak in smsc75xx_bind

In the Linux kernel, the following vulnerability has been resolved: net: usb: fix memory leak in smsc75xx_bind Syzbot reported memory leak in smsc75xx_bind(). The problem was is non-freed memory in case of errors after memory allocation. backtrace: [<ffffffff84245b62>] kmalloc include/linux/slab.h:556 [inline] [<ffffffff84245b62>] kzalloc include/linux/slab.h:686 [inline] [<ffffffff84245b62>] smsc75xx_bind+0x7a/0x334 drivers/net/usb/smsc75xx.c:1460 [<ffffffff82b5b2e6>] usbnet_probe+0x3b6/0xc30 drivers/net/usb/usbnet.c:1728

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47171 is a Linux kernel memory leak in the SMSC75xx USB Ethernet driver. If driver binding fails after allocation, memory may not be freed. The source bundle does not provide CVSS, confirmed exploitation, or impact beyond leaked kernel memory, so urgency depends on whether affected kernels and this driver are in use.

Executive priority

Treat this as a targeted kernel maintenance item, not an emergency, unless affected USB Ethernet use is confirmed on critical systems. Patch through normal kernel update channels and track vendor guidance.

Technical view

The flaw is in drivers/net/usb/smsc75xx.c, smsc75xx_bind(). Syzbot observed kmalloc/kzalloc memory not freed on later error paths during usbnet_probe(). Linux stable commits resolve the leak across affected branches. The bundle lists Linux 2.6.34 through 5.13-era versions and several stable points as affected.

Likely exposure

Exposure appears limited to Linux systems running affected kernel versions with the SMSC75xx USB Ethernet driver reachable or loaded. The sources do not specify remote reachability, default driver state, or distribution-specific package status.

Exploitation context

The bundle shows syzbot discovery and kernel fixes, but no KEV listing and no cited evidence of active exploitation. The available detail supports a reliability or resource-leak concern, not a confirmed compromise path.

Researcher notes

Evidence is narrow: a memory leak in an error path after allocation during driver bind. No CVSS, CWE, exploitability analysis, or distribution mapping is provided. Avoid assuming remote exploitability without additional vendor evidence.

Mitigation direction

  • Check vendor or distribution kernel advisories for fixed packages.
  • Update affected Linux kernels to versions containing the referenced stable fixes.
  • Prioritize systems using SMSC75xx USB Ethernet adapters or the smsc75xx driver.
  • If updates are delayed, review vendor guidance for driver-specific risk reduction.

Validation and detection

  • Inventory Linux kernel versions against the affected version list.
  • Confirm whether the smsc75xx driver is present, loaded, or required.
  • Verify installed kernels include the applicable stable fix commit.
  • Review vulnerability scanner findings against distribution backport notes.
Prepared
Confidence
medium
Sources
10

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-2021-47171 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
9Source 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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxd0cad871703b898a442e4049c532ec39168e5b57, d0cad871703b898a442e4049c532ec39168e5b57, d0cad871703b898a442e4049c532ec39168e5b57, d0cad871703b898a442e4049c532ec39168e5b57, d0cad871703b898a442e4049c532ec39168e5b57, d0cad871703b898a442e4049c532ec39168e5b57, d0cad871703b898a442e4049c532ec39168e5b57, d0cad871703b898a442e4049c532ec39168e5b57unaffected
LinuxLinux2.6.34, 0, 4.4.271, 4.9.271, 4.14.235, 4.19.193, 5.4.124, 5.10.42, 5.12.9, 5.13affected
Weakness

CWE details

No CWE listed

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