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NVD / CVE Program· CNA redhat

CVE-2021-4204: An out-of-bounds (OOB) memory access flaw was found in the Linux kernel's eBPF due to an Improper Input Validation.

Noroxi assessment

Priority: Monitor (action score 28/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.2% (FIRST EPSS); higher than 69.2% of all records.
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: bpftool (AlmaLinux:8) 4.18.0-553.el8_10; kernel (AlmaLinux:8) 4.18.0-553.el8_10; kernel-abi-stablelists (AlmaLinux:8) 4.18.0-553.el8_10.

Low priority for now. Upgrade to bpftool (AlmaLinux:8) 4.18.0-553.el8_10; kernel (AlmaLinux:8) 4.18.0-553.el8_10; kernel-abi-stablelists (AlmaLinux:8) 4.18.0-553.el8_10 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

An out-of-bounds (OOB) memory access flaw was found in the Linux kernel's eBPF due to an Improper Input Validation. This flaw allows a local attacker with a special privilege to crash the system or leak internal information.

HighCVSS 7.1 · v3.1—Proof of concept Fix available
Published
Aug 24, 2022
Updated
Nov 2, 2026
EPSS
1.2% · 69th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-4204

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel
debiandebian linux
redhatenterprise linux
netapph300s firmware
netapph300s
netapph500s firmware
netapph500s
netapph700s firmware
netapph700s
netapph410s firmware
netapph410s
netapph410c firmware

and 1 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux11.0
  • linux linux kernelbefore 5.8.0
  • linux linux kernel5.8.0
  • netapp h300s firmwareall versions
  • netapp h410c firmwareall versions
  • netapp h410s firmwareall versions
  • netapp h500s firmwareall versions
  • netapp h700s firmwareall versions
  • redhat enterprise linux9.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • n/a kernel

    • Affects Linux kernel v5.8 or lateraffected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8bpftoolbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernelbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-abi-stablelistsbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-corebefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-cross-headersbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-debugbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-debug-corebefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-debug-develbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-debug-modulesbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-debug-modules-extrabefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-develbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-docbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-headersbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-modulesbefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-modules-extrabefore 4.18.0-553.el8_104.18.0-553.el8_10
AlmaLinux:8kernel-rtbefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10
AlmaLinux:8kernel-rt-corebefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10
AlmaLinux:8kernel-rt-debugbefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10
AlmaLinux:8kernel-rt-debug-corebefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10
AlmaLinux:8kernel-rt-debug-develbefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10
AlmaLinux:8kernel-rt-debug-kvmbefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10
AlmaLinux:8kernel-rt-debug-modulesbefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10
AlmaLinux:8kernel-rt-debug-modules-extrabefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10
AlmaLinux:8kernel-rt-develbefore 4.18.0-553.rt7.342.el8_104.18.0-553.rt7.342.el8_10

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2021-4037Aug 24, 2022 · Kernel: security regression for cve-2018-13405
    17Monitor
  • ← EarlierCVE-2021-4159Aug 24, 2022 · A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures.
    17Monitor
  • Later →CVE-2022-2978Aug 24, 2022 · A flaw use after free in the Linux kernel NILFS file system was found in the way user triggers function security_inode_alloc to fail with fo
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:kernel-rt4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-core4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-core4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-devel4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-kvm4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-modules4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-modules-extra4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-devel4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-kvm4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-modules4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-modules-extra4.18.0-553.rt7.342.el8_10 · AlmaLinux:8Package registry (OSV)
debian:linux5.17.3-1 · Debian:12Package registry (OSV)
opensuse:dtb-aarch645.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-64kb5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-debug5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-default5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-default-base5.14.21-150400.24.11.1.150400.24.3.6 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-docs5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-kvmsmall5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-obs-build5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-obs-qa5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-source5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-syms5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:kernel-zfcpdump5.14.21-150400.24.11.1 · openSUSE:Leap 15.4Package registry (OSV)
red hat:bpftool0:4.18.0-372.91.1.el8_6 · Red Hat:rhel_eus:8.6::baseosPackage registry (OSV)
red hat:bpftool-debuginfo0:4.18.0-372.91.1.el8_6 · Red Hat:rhev_hypervisor:4.4::el8Package registry (OSV)
red hat:kernel0:4.18.0-372.91.1.el8_6 · Red Hat:rhel_eus:8.6::baseosPackage registry (OSV)
red hat:kernel-abi-stablelists0:4.18.0-372.91.1.el8_6 · Red Hat:rhel_eus:8.6::baseosPackage registry (OSV)
red hat:kernel-debug-debuginfo0:4.18.0-372.91.1.el8_6 · Red Hat:rhev_hypervisor:4.4::el8Package registry (OSV)

+21

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:622022-02-24

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. First PoC-182 d
  2. Published
  3. TodayNov 3, 2026+1532 d

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-20 · Improper Input Validation

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records