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Linux KernelOperating system · Linux

CVE-2021-47652

MEDIUM · 5.5 CVSS v3.1 Published 2025-02-26
Fix available
A fix is available. Upgrade to 4.9.311 / 4.14.276 or later.
See remediation →
57/100
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: video: fbdev: smscufx: Fix null-ptr-deref in ufx_usb_probe() I got a null-ptr-deref report: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:fb_destroy_modelist+0x38/0x100 ... Call Trace: ufx_usb_probe.cold+0x2b5/0xac1 [smscufx] usb_probe_interface+0x1aa/0x3c0 [usbcore] really_probe+0x167/0x460 ... ret_from_fork+0x1f/0x30 If fb_alloc_cmap() fails in ufx_usb_probe(), fb_destroy_modelist() will be called to destroy modelist in the error handling path. But modelist has not been initialized yet, so it will result in null-ptr-deref. Initialize modelist before calling fb_alloc_cmap() to fix this bug.

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-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference 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:>= 3.2, < 4.9.311>= 4.10, < 4.14.276>= 4.15, < 4.19.238>= 4.20, < 5.4.189>= 5.5, < 5.10.110>= 5.11, < 5.15.33>= 5.16, < 5.16.19>= 5.17, < 5.17.2

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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 4.9.311 / 4.14.276 / 4.19.238 or later
Fixed in 4.9.3114.14.2764.19.238
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to kernel 4.9.311 or higher (for 4.9.x branch), 4.14.276 or higher (for 4.14.x branch), 4.19.238 or higher (for 4.19.x branch), or 5.4.189 or higher (for 5.4.x branch)

  1. Identify current kernel version using 'uname -r' or 'cat /proc/version'
  2. Consult your Linux distribution's documentation for kernel upgrade procedures (e.g., apt-get update && apt-get upgrade for Debian/Ubuntu, yum update for RHEL/CentOS, or dnf upgrade for Fedora)
  3. Reboot the system to load the new kernel
  4. Verify the new kernel version is running with 'uname -r' and confirm it is at or above the fixed version for your branch
Caveat Kernel upgrades may require system reboot and could have compatibility implications with custom drivers or modules; test in staging environment first

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 $2,850. 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-2021-47652 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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