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Linux KernelOperating system · Linux

CVE-2021-47137

CRITICAL · 9.8 CVSS v3.1 Published 2024-03-25
Fix available
A fix is available. Upgrade to 5.4.124 / 5.10.42 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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: net: lantiq: fix memory corruption in RX ring In a situation where memory allocation or dma mapping fails, an invalid address is programmed into the descriptor. This can lead to memory corruption. If the memory allocation fails, DMA should reuse the previous skb and mapping and drop the packet. This patch also increments rx drop counter.

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-770

The application allocates memory, connections, or handles in response to a request without enforcing any cap, so a modest amount of malicious traffic exhausts the resource and denies service to everyone else. The fix is enforcing quotas, limits, and timeouts on what any single request or client can consume.

General guidance for the resource allocation without limits 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:>= 4.20, < 5.4.124>= 5.5, < 5.10.42>= 5.11, < 5.12.9= 5.13

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 5.4.124 / 5.10.42 / 5.12.9 or later
Fixed in 5.4.1245.10.425.12.9
Vendor patch git.kernel.org →
Recommended fix High confidence

5.4.124, 5.10.42, 5.12.9, or any version after 5.13 (depending on which branch is in use)

  1. Identify the currently running kernel version using 'uname -r' or 'cat /proc/version'
  2. Check if the current version is within an affected range: >= 4.20 and < 5.4.124, >= 5.5 and < 5.10.42, >= 5.11 and < 5.12.9, or exactly 5.13
  3. Obtain a kernel upgrade from your Linux distribution's stable repository. For mainline, download 5.4.124 or newer for the 5.4 branch, 5.10.42 or newer for the 5.10 branch, 5.12.9 or newer for the 5.12 branch, or any version after 5.13 for the 5.13 branch
  4. Install the new kernel following your distribution's standard kernel upgrade procedure (e.g., package manager install, manual compilation, or live patch)
  5. Reboot the system into the new kernel
  6. Verify the fix is applied by checking the kernel version and confirming the lantiq driver no longer has the memory corruption vulnerability
Caveat Kernel upgrades may require matching kernel modules or firmware; ensure all hardware drivers are compatible with the new kernel version before production deployment

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 $2,300. 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-2021-47137 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data