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Vulnerabilities

Vulnerability · CVE-2021-4159

A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures.

Published Aug 24, 2022 · catalog updated Nov 2, 2026 · linux kernel

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2021-4159. EPSS is 0.25%. Act only if a listed version of linux kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium4.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.25%
Remediation
Version ranges on file
Affected products
cpe debian/debian linux · cpe linux/linux kernel · cpe redhat/enterprise linux

A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures. Internal memory locations could be returned to userspace. A local attacker with the permissions to insert eBPF code to the kernel can use this to leak internal kernel memory details defeating some of the exploit mitigations in place for the kernel.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe debian/debian linux10.0
  • cpe linux/linux kernel< 5.7
  • cpe redhat/enterprise linux8.0

How to fix CVE-2021-4159

  • Upgrade

    CVE-2021-4159 lists a fix boundary at 5.7. Compare the installed build with that boundary before you change production.

  • Version check

    Affected < 5.7

  • Advisory

    Open the cve_org record and follow its fix.

  • Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-4159. EPSS is 0.25%. Act only if a listed version of linux kernel is installed.

Which versions are affected?

Compare what you have installed with debian/debian linux 10.0; linux/linux kernel < 5.7; redhat/enterprise linux 8.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-202. EPSS 0.25%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 24, 2022 · NIST NVD

    Detected

    A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures. Internal memory locations could be returned to userspace. A local attacker with the permissions to insert eBPF code to the kernel can use this to leak internal kernel memory details defeating some of the exploit mitigations in place for the kernel.

  2. Nov 2, 2026 · NIST NVD

    Updated

    A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures. Internal memory locations could be returned to userspace. A local attacker with the permissions to insert eBPF code to the kernel can use this to leak internal kernel memory details defeating some of the exploit mitigations in place for the kernel.

Sources

  • CVE.orgVulnerability recordCVE-2021-4159

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2021-4159

    A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures. Internal memory locations could be returned to userspace. A local attacker with the permissions to insert eBPF code to the kernel can use this to leak internal kernel memory deta

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • NIST NVDNov 3, 2026