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Linux KernelOperating system · Linux

CVE-2021-4023

MEDIUM · 5.5 CVSS v3.1 Published 2022-03-10
Fix available
A fix is available. Upgrade to after 5.14 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
A flaw was found in the io-workqueue implementation in the Linux kernel versions prior to 5.15-rc1. The kernel can panic when an improper cancellation operation triggers the submission of new io-uring operations during a shortage of free space. This flaw allows a local user with permissions to execute io-uring requests to possibly crash the system.

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-200

The application discloses data — error detail, internal paths, tokens, or other users' records — to someone who shouldn't see it. On its own it can look minor, but it hands attackers the map they need for a larger attack. Remediation is about minimising what's returned and enforcing authorization on every piece of data.

General guidance for the information exposure 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:<= 5.14
FedoraOperating system
Affected:= 35

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 a release after 5.14
Vendor patch bugzilla.redhat.com →
Recommended fix High confidence

Linux Kernel 5.15 or later; Fedora 35+ with kernel-5.15.x

  1. 1. Back up critical data and verify you have a way to recover if the system fails to boot after the kernel update
  2. 2. Update the system package repository: On Fedora, run `sudo dnf check-update`
  3. 3. Install the latest kernel package: Run `sudo dnf update kernel` (or `sudo dnf update` for all packages)
  4. 4. Verify the new kernel version is installed: Run `rpm -q kernel` to list installed kernels
  5. 5. Restart the system to boot into the updated kernel: Run `sudo reboot`
  6. 6. After reboot, confirm the running kernel version is 5.15 or later: Run `uname -r`
  7. 7. Verify the fix is applied by checking that io-uring operations no longer cause kernel panics under the previously vulnerable conditions
Caveat Kernel upgrades may require reboot and can introduce compatibility issues with proprietary kernel modules or older drivers

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

We can identify the exact fixed release, upgrade, and verify it in staging — typical engagement from $900. 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-2021-4023 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