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NVD / CVE Program· CNA Linux

CVE-2021-47579: ovl: fix warning in ovl_create_real()

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.23% (FIRST EPSS).
  • 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: Linux Linux 1f5573cfe7a7056e80a92c7a037a3e69f3a13d1c, 445d2dc63e5871d218f21b8f62ab29ac72f2e6b8, 6859985a2fbda5d1586bf44538853e1be69e85f7.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1f5573cfe7a7056e80a92c7a037a3e69f3a13d1c, 445d2dc63e5871d218f21b8f62ab29ac72f2e6b8, 6859985a2fbda5d1586bf44538853e1be69e85f7 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

In the Linux kernel, the following vulnerability has been resolved: ovl: fix warning in ovl_create_real() Syzbot triggered the following warning in ovl_workdir_create() -> ovl_create_real(): if (!err && WARN_ON(!newdentry->d_inode)) { The reason is that the cgroup2 filesystem returns from mkdir without instantiating the new dentry. Weird filesystems such as this will be rejected by overlayfs at a later stage during setup, but to prevent such a warning, call ovl_mkdir_real() directly from ovl_workdir_create() and reject this case early.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jun 19, 2024
Updated
Jun 17, 2026
EPSS
0.2% · 14th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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
  • No public exploit code on record
  • A fix has been released

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

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • 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

Affected versions

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

  • linux linux kernelbefore 4.19.222
  • linux linux kernel4.20 and later · before 5.4.168
  • linux linux kernel5.5 and later · before 5.10.88
  • linux linux kernel5.11 and later · before 5.15.11

Versions reported by the vendor

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

  • Linux Linux

    • 3.18affected
    • e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c and later · before 445d2dc63e5871d218f21b8f62ab29ac72f2e6b8affected · git
    • e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c and later · before f9f300a92297be8250547347fd52216ef0177ae0affected · git
    • e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c and later · before 6859985a2fbda5d1586bf44538853e1be69e85f7affected · git
    • e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c and later · before d2ccdd4e4efab06178608a34d7bfb20a54104c02affected · git
    • e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c and later · before 1f5573cfe7a7056e80a92c7a037a3e69f3a13d1caffected · git
    • before 3.18not affected · semver
    • 4.19.222 and later · up to and including 4.19.*not affected · semver
    • 5.4.168 and later · up to and including 5.4.*not affected · semver
    • 5.10.88 and later · up to and including 5.10.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:8bpftoolbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernelbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-abi-stablelistsbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-corebefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-cross-headersbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-debugbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-debug-corebefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-debug-develbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-debug-modulesbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-debug-modules-extrabefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-develbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-docbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-headersbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-modulesbefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-modules-extrabefore 4.18.0-553.16.1.el8_104.18.0-553.16.1.el8_10
AlmaLinux:8kernel-rtbefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.el8_10
AlmaLinux:8kernel-rt-corebefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.el8_10
AlmaLinux:8kernel-rt-debugbefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.el8_10
AlmaLinux:8kernel-rt-debug-corebefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.el8_10
AlmaLinux:8kernel-rt-debug-develbefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.el8_10
AlmaLinux:8kernel-rt-debug-kvmbefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.el8_10
AlmaLinux:8kernel-rt-debug-modulesbefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.el8_10
AlmaLinux:8kernel-rt-debug-modules-extrabefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.el8_10
AlmaLinux:8kernel-rt-develbefore 4.18.0-553.16.1.rt7.357.el8_104.18.0-553.16.1.rt7.357.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-2021-47577Jun 19, 2024 · io-wq: check for wq exit after adding new worker task_work
    18Monitor
  • ← EarlierCVE-2021-47578Jun 19, 2024 · scsi: scsi_debug: Don't call kcalloc() if size arg is zero
    22Monitor
  • Later →CVE-2021-47580Jun 19, 2024 · scsi: scsi_debug: Fix type in min_t to avoid stack OOB
    28Monitor

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
Linux Linux1f5573cfe7a7056e80a92c7a037a3e69f3a13d1cVendor (CNA)
Linux Linux445d2dc63e5871d218f21b8f62ab29ac72f2e6b8Vendor (CNA)
Linux Linux6859985a2fbda5d1586bf44538853e1be69e85f7Vendor (CNA)
Linux Linuxd2ccdd4e4efab06178608a34d7bfb20a54104c02Vendor (CNA)
Linux Linuxf9f300a92297be8250547347fd52216ef0177ae0Vendor (CNA)
almalinux:bpftool4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-abi-stablelists4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-core4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-cross-headers4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-core4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-devel4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules-extra4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-devel4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-doc4.18.0-553.16.1.el8_10 · AlmaLinux:8Package registry (OSV)
debian:linux5.15.15-1 · Debian:12Package registry (OSV)
red hat:bpftool-debuginfo0:7.3.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-debuginfo0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel-matched0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debuginfo0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel-matched0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-debuginfo0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel-matched0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debuginfo0:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debuginfo-common-aarch640:5.14.0-427.13.1.el9_4 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)

+2

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

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.

No dated events beyond publication.

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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
none
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
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. 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