A flaw was found in the Linux kernel.
Priority LOW 21CWE-665Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- High
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 12 fixed, 1 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
A flaw was found in the Linux kernel. A corrupted timer tree caused the task wakeup to be missing in the timerqueue_add function in lib/timerqueue.c. This flaw allows a local attacker with special user privileges to cause a denial of service, slowing and eventually stopping the system while running OSP.
Why it matters now
EPSS 0.00382 32nd percentileScored 2026-11-07
Fix Partial Red Hat: 6 advisoriesRed Hat: 12 fixed, 1 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | kernel | Kernel 5.3 rc1 | — | No fix listed | CNA |
- kernel Vendor— Affected Kernel 5.3 rc1 Fixed in — No fix listed CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | before 5.4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.4:-:*:*:*:*:*:* | 5.4 | Vulnerable | Linux |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions before 5.4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.4:-:*:*:*:*:*:* Versions 5.4 Vulnerable ·Linux
- 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 6 advisories
- RHSA-2021:4871 Released 2021-11-30 · Red Hat rating Importantkernel security and bug fix update
- Red Hat CodeReady Linux Builder EUS (v. 8.2) kernel-tools-libs-devel-4.18.0-193.70.1.el8_2
- Red Hat Enterprise Linux BaseOS EUS (v. 8.2) bpftool-4.18.0-193.70.1.el8_2, kernel-4.18.0-193.70.1.el8_2, kernel-abi-whitelists-4.18.0-193.70.1.el8_2 +19
- RHSA-2021:4875 Released 2021-11-30 · Red Hat rating Importantkernel-rt security and bug fix update
- Red Hat Enterprise Linux Real Time EUS (v. 8.2) kernel-rt-4.18.0-193.70.1.rt13.120.el8_2, kernel-rt-core-4.18.0-193.70.1.rt13.120.el8_2, kernel-rt-debug-4.18.0-193.70.1.rt13.120.el8_2 +7
- Red Hat Enterprise Linux Real Time for NFV EUS (v. 8.2) kernel-rt-4.18.0-193.70.1.rt13.120.el8_2, kernel-rt-core-4.18.0-193.70.1.rt13.120.el8_2, kernel-rt-debug-4.18.0-193.70.1.rt13.120.el8_2 +9
- RHSA-2021:4647 Released 2021-11-15 · Red Hat rating Importantkernel security update
- Red Hat CodeReady Linux Builder (v. 8) kernel-tools-libs-devel-4.18.0-348.2.1.el8_5
- Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-348.2.1.el8_5, kernel-4.18.0-348.2.1.el8_5, kernel-abi-stablelists-4.18.0-348.2.1.el8_5 +19
Show 3 more Red Hat advisories
- RHSA-2021:4650 Released 2021-11-15 · Red Hat rating Importantkernel security, bug fix, and enhancement update
- Red Hat Enterprise Linux BaseOS EUS (v.8.4) bpftool-4.18.0-305.28.1.el8_4, kernel-4.18.0-305.28.1.el8_4, kernel-abi-stablelists-4.18.0-305.28.1.el8_4 +19
- Red Hat Enterprise Linux CRB EUS (v.8.4) kernel-tools-libs-devel-4.18.0-305.28.1.el8_4
- RHSA-2021:4648 Released 2021-11-15 · Red Hat rating Importantkernel-rt security and bug fix update
- Red Hat Enterprise Linux NFV EUS (v.8.4) kernel-rt-4.18.0-305.28.1.rt7.100.el8_4, kernel-rt-core-4.18.0-305.28.1.rt7.100.el8_4, kernel-rt-debug-4.18.0-305.28.1.rt7.100.el8_4 +9
- Red Hat Enterprise Linux RT EUS (v.8.4) kernel-rt-4.18.0-305.28.1.rt7.100.el8_4, kernel-rt-core-4.18.0-305.28.1.rt7.100.el8_4, kernel-rt-debug-4.18.0-305.28.1.rt7.100.el8_4 +7
- RHSA-2021:4646 Released 2021-11-15 · Red Hat rating Importantkernel-rt security and bug fix update
- Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt-4.18.0-348.2.1.rt7.132.el8_5, kernel-rt-core-4.18.0-348.2.1.rt7.132.el8_5, kernel-rt-debug-4.18.0-348.2.1.rt7.132.el8_5 +9
- Red Hat Enterprise Linux for Real Time (v. 8) kernel-rt-4.18.0-348.2.1.rt7.132.el8_5, kernel-rt-core-4.18.0-348.2.1.rt7.132.el8_5, kernel-rt-debug-4.18.0-348.2.1.rt7.132.el8_5 +7
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Will not fix |
| Red Hat CodeReady Linux Builder (v. 8) | Fixed | RHSA-2021:4647 |
| Red Hat CodeReady Linux Builder EUS (v. 8.2) | Fixed | RHSA-2021:4871 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2021:4647 |
| Red Hat Enterprise Linux BaseOS EUS (v. 8.2) | Fixed | RHSA-2021:4871 |
| Red Hat Enterprise Linux BaseOS EUS (v.8.4) | Fixed | RHSA-2021:4650 |
| Red Hat Enterprise Linux CRB EUS (v.8.4) | Fixed | RHSA-2021:4650 |
| Red Hat Enterprise Linux NFV EUS (v.8.4) | Fixed | RHSA-2021:4648 |
| Red Hat Enterprise Linux RT EUS (v.8.4) | Fixed | RHSA-2021:4648 |
| Red Hat Enterprise Linux Real Time EUS (v. 8.2) | Fixed | RHSA-2021:4875 |
| Red Hat Enterprise Linux Real Time for NFV (v. 8) | Fixed | RHSA-2021:4646 |
| Red Hat Enterprise Linux Real Time for NFV EUS (v. 8.2) | Fixed | RHSA-2021:4875 |
| Red Hat Enterprise Linux for Real Time (v. 8) | Fixed | RHSA-2021:4646 |
Not affected: 3 products
- Red Hat Enterprise Linux 5
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2021-20317
- 2026-10-03 Alias added: GHSA-hf76-5hm2-g68j
References
Advisory 4
Sources
- CVE-2021-20317 · CVE Program
- CVE-2021-20317 · NVD
- FIRST EPSS
- GHSA-hf76-5hm2-g68j · GitHub Advisory Database · CC BY 4.0
- CVE-2021-20317 · Red Hat security data · CC BY 4.0
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