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Linux KernelOperating system · Linux

CVE-2021-47101

HIGH · 7.1 CVSS v3.1 Published 2024-03-04
Fix available
A fix is available. Upgrade to 5.15.12 or later.
See remediation →
73/100
Remediation priority · Elevated
Zero-click Patch available

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 · unedited
In the Linux kernel, the following vulnerability has been resolved: asix: fix uninit-value in asix_mdio_read() asix_read_cmd() may read less than sizeof(smsr) bytes and in this case smsr will be uninitialized. Fail log: BUG: KMSAN: uninit-value in asix_check_host_enable drivers/net/usb/asix_common.c:82 [inline] BUG: KMSAN: uninit-value in asix_check_host_enable drivers/net/usb/asix_common.c:82 [inline] drivers/net/usb/asix_common.c:497 BUG: KMSAN: uninit-value in asix_mdio_read+0x3c1/0xb00 drivers/net/usb/asix_common.c:497 drivers/net/usb/asix_common.c:497 asix_check_host_enable drivers/net/usb/asix_common.c:82 [inline] asix_check_host_enable drivers/net/usb/asix_common.c:82 [inline] drivers/net/usb/asix_common.c:497 asix_mdio_read+0x3c1/0xb00 drivers/net/usb/asix_common.c:497 drivers/net/usb/asix_common.c:497

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
How this class of weakness works · CWE-908

Memory or a resource is used before it has been initialised, so its contents are whatever happened to be there — sometimes leaking earlier data, sometimes values an attacker can influence. Behaviour becomes unpredictable and occasionally exploitable. Remediation is initialising every resource before use and ensuring initialisation happens on all code paths.

General guidance for the use of uninitialized resource class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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 data
Linux KernelOperating system
Affected:>= 4.9, < 5.15.12= 5.16

CVSS 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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

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.

dbcve · scoped
Upgrade available Upgrade to 5.15.12 or later
Fixed in 5.15.12
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 5.15.12 or later, or 5.16.x beyond 5.16

  1. Identify the current Linux kernel version using `uname -r` or `cat /proc/version`
  2. If running kernel >= 4.9 and < 5.15.12, or exactly 5.16, plan for an upgrade
  3. Apply the vendor patch from commit 8035b1a2a37a29d8c717ef84fca8fe7278bc9f03 to the asix driver, OR
  4. Upgrade to Linux kernel 5.15.12 or later (includes the fix)
  5. If using kernel 5.16.x, upgrade to a version beyond 5.16 that contains this fix
  6. Reboot into the patched/updated kernel
  7. Verify the fix by checking the asix_common.c file contains the initialization of smsr before use

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-47101 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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