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TI-2021-03610 Aliases CVE-2021-20321

Race condition in kernel

Priority LOW 21CWE-362Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 4 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

A race condition accessing file object in the Linux kernel OverlayFS subsystem was found in the way users do rename in specific way with OverlayFS. A local user could use this flaw to crash the system.

Why it matters now

EPSS 0.00216 12th percentileScored 2026-11-07
Fix Partial Red Hat: 2 advisoriesRed Hat: 4 fixed, 1 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
—kernelkernel 5.15-rc5—No fix listedCNA
  • kernel Vendor— Affected kernel 5.15-rc5 Fixed in — No fix listed CNA

CPE configurations NVD · 10

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*before 5.15VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:-:*:*:*:*:*:*5.15VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*5.15 rc1VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*5.15 rc2VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*5.15 rc3VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*5.15 rc4VulnerableLinux
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*7.0VulnerableRed Hat
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*8.0VulnerableRed Hat
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*9.0VulnerableDebian
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*10.0VulnerableDebian
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions before 5.15 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:-:*:*:*:*:*:* Versions 5.15 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:* Versions 5.15 rc1 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:* Versions 5.15 rc2 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:* Versions 5.15 rc3 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:* Versions 5.15 rc4 Vulnerable ·Linux
  • cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* Versions 7.0 Vulnerable ·Red Hat
  • cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Red Hat
  • cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
  • cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian

Remediation

Red Hat 2 advisories

  • RHSA-2021:5227 Released 2021-12-21 · Red Hat rating Moderate
    kernel security and bug fix update
    • Red Hat CodeReady Linux Builder (v. 8) kernel-tools-libs-devel-4.18.0-348.7.1.el8_5
    • Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-348.7.1.el8_5, kernel-4.18.0-348.7.1.el8_5, kernel-abi-stablelists-4.18.0-348.7.1.el8_5 +20
  • RHSA-2021:5241 Released 2021-12-21 · Red Hat rating Moderate
    kernel-rt security and bug fix update
    • Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt-4.18.0-348.7.1.rt7.137.el8_5, kernel-rt-core-4.18.0-348.7.1.rt7.137.el8_5, kernel-rt-debug-4.18.0-348.7.1.rt7.137.el8_5 +9
    • Red Hat Enterprise Linux for Real Time (v. 8) kernel-rt-4.18.0-348.7.1.rt7.137.el8_5, kernel-rt-core-4.18.0-348.7.1.rt7.137.el8_5, kernel-rt-debug-4.18.0-348.7.1.rt7.137.el8_5 +7

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat CodeReady Linux Builder (v. 8)Fixed RHSA-2021:5227
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2021:5227
Red Hat Enterprise Linux Real Time for NFV (v. 8)Fixed RHSA-2021:5241
Red Hat Enterprise Linux for Real Time (v. 8)Fixed RHSA-2021:5241
Not affected: 4 products
  • Red Hat Enterprise Linux 5
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 9
  • Red Hat Enterprise Linux BaseOS (v. 8)

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-20321

References

Advisory 3

Other 1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences