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Critical· 9.8official fix available

CVE-2021-47496

A flaw in the Linux kernel’s TLS implementation can corrupt memory when error codes are handled incorrectly. The bug was fixed by correcting the sign of error values and adding safeguards. It affects all Linux kernel releases, including 5.15.

publishedMay 22, 2024
last modifiedAug 4, 2026
sourcesNVD
severity · cvss
9.8
critical · how bad it is
exploitation · epss
<1%
39th percentile · chance of exploitation in 30 days
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
auto-deletes from the system
counting…on Sep 4, 2026

An official fix is available, so this entry is kept for 30 days and then removed automatically.

01

Who is affected

Linux kernel, including version 5.15 and other kernel releases.

02

Real-world impact

An attacker could exploit the memory corruption to execute arbitrary code or crash the system, potentially taking control of the affected machine.

03

Why this severity

The CVSS score of 9.8 reflects that the vulnerability can compromise confidentiality, integrity, and availability without any authentication or user interaction, making it a critical risk.

04

What to do about it

official fix available
recommended steps
  1. 01Update the Linux kernel to a version that includes the CVE-2021-47496 fix.

NVD-referenced vendor advisory

05

Timeline

  1. May 22, 2024 · May 22, 2024
    Published
    Disclosed and added to the National Vulnerability Database.
  2. Aug 4, 2026 · 2d ago
    Advisory updated
    The NVD record was last revised.
  3. Aug 5, 2026 · 1d ago
    Official fix available
    A vendor patch or mitigation now exists — see the remediation steps above.
06

How it’s attacked

Attack vectorNetwork (remote)
Attack complexityLow
Privileges requiredNone
User interactionNone needed
ScopeUnchanged
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
07

References & advisories

NVD advisory ↗Search advisories ↗
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
CVE-2021-47496: A flaw in the Linux kernel’s TLS implementation can corrupt memory whe · Vulnary