CVE-2025-21971

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-04-01. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

net_sched: Prevent creation of classes with TC_H_ROOT

The function qdisc_tree_reduce_backlog() uses TC_H_ROOT as a termination condition when traversing up the qdisc tree to update parent backlog counters. However, if a class is created with classid TC_H_ROOT, the traversal terminates prematurely at this class instead of reaching the actual root qdisc, causing parent statistics to be incorrectly maintained. In case of DRR, this could lead to a crash as reported by Mingi Cho.

Prevent the creation of any Qdisc class with classid TC_H_ROOT (0xFFFFFFFF) across all qdisc types, as suggested by Jamal.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
9.1%
KEV
Not listed

Published

April 1, 2025

Last Modified

November 3, 2025

References (10)

Patch Availability(31)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-16.04-edge (4.15.0.237.249~16.04.1) @ xenial2026-05-30ubuntu
ubuntulinux-virtual-lts-xenial (4.4.0.268.274) @ xenial2026-05-30ubuntu
ubuntulinux-tools-azure (4.15.0.1188.203~14.04.1) @ trusty2026-05-30ubuntu
ubuntulinux-tools-fips (5.15.0.140.80) @ jammy2026-05-30ubuntu
ubuntulinux-tools-fips (4.4.0.1113.114) @ xenial2026-05-30ubuntu
ubuntulinux-tools-gcp-fips (4.15.0.2081.79) @ bionic2026-05-30ubuntu
ubuntulinux-tools-azure-edge (4.15.0.1188.203~16.04.1) @ xenial2026-05-30ubuntu
ubuntulinux-tools-azure-fips (4.15.0.2097.93) @ bionic2026-05-30ubuntu
ubuntulinux-virtual-lts-xenial (4.4.0.268.302~14.04.1) @ trusty2026-05-30ubuntu
ubuntulinux-virtual-hwe-20.04-edge (5.15.0.140.135) @ jammy2026-05-30ubuntu
ubuntulinux-tools-aws (4.4.0.1143.140) @ trusty2026-05-30ubuntu
ubuntulinux-tools-gcp-lts-22.04 (5.15.0.1083.79) @ jammy2026-05-30ubuntu
ubuntulinux-tools-realtime (6.8.1-1022.23) @ noble2026-05-30ubuntu
ubuntulinux-tools-gcp-edge (5.15.0.1083.92~20.04.1) @ focal2026-05-30ubuntu
ubuntulinux-tools-gcp-fips (5.15.0.1083.73) @ jammy2026-05-30ubuntu
ubuntulinux-virtual (6.8.0-60.63) @ noble2026-05-30ubuntu
ubuntulinux-virtual-hwe-18.04-edge (5.4.0.216.208) @ focal2026-05-30ubuntu
ubuntulinux-tools-gke (6.8.0-1025.29) @ noble2026-05-30ubuntu
ubuntulinux-tools-oem-24.04a (6.8.0-1028.28) @ noble2026-05-30ubuntu
ubuntulinux-tools-nvidia-tegra-rt (5.15.0.1037.37) @ jammy2026-05-30ubuntu
ubuntulinux-virtual-hwe-18.04-edge (5.4.0.216.236~18.04.1) @ bionic2026-05-30ubuntu
ubuntulinux-tools-azure-nvidia (6.8.0-1016.17) @ noble2026-05-30ubuntu
ubuntulinux-tools-aws (6.11.0-1014.15) @ oracular2026-05-30ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k (6.8.0-1028.31.1) @ noble2026-05-30ubuntu
ubuntulinux-tools-kvm (5.4.0.1133.129) @ focal2026-05-30ubuntu
ubuntulinux-tools-gcp-fips (5.4.0.1149.91) @ focal2026-05-30ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.4.0-1064 (5.4.0-1064.68) @ focal2026-05-30ubuntu
ubuntulinux-tools-azure-fips (5.4.0.1151.88) @ focal2026-05-30ubuntu
ubuntulinux-virtual-hwe-24.04-edge (6.11.0-26.26~24.04.1) @ noble2026-05-30ubuntu
ubuntulinux-tools-realtime (5.15.0.1084.88) @ jammy2026-05-30ubuntu
linuxKernel @ 5.4.292—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(25)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 13× in last 7d / 46× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-24 14:17 UTCEPSS rescore
  2. 2026-07-24 10:41 UTCOSV refresh
  3. 2026-07-23 14:17 UTCEPSS rescore
  4. 2026-07-23 02:50 UTCEG score recompute
  5. 2026-07-22 14:07 UTCEPSS rescore
  6. 2026-07-22 14:07 UTCEPSS rescore
  7. 2026-07-21 15:24 UTCEPSS rescore
  8. 2026-07-20 17:07 UTCEPSS rescore
  9. 2026-07-19 14:30 UTCEPSS rescore
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  11. 2026-07-19 02:28 UTCEPSS rescore
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  13. 2026-07-18 10:03 UTCEPSS rescore
  14. 2026-07-16 17:02 UTCEPSS rescore
  15. 2026-07-15 16:57 UTCEPSS rescore
  16. 2026-07-15 16:57 UTCEPSS rescore
  17. 2026-07-15 01:59 UTCEPSS rescore
  18. 2026-07-13 22:29 UTCEPSS rescore
  19. 2026-07-13 22:29 UTCEPSS rescore
  20. 2026-07-13 06:12 UTCEPSS rescore
  21. 2026-07-13 06:12 UTCEPSS rescore
  22. 2026-07-12 05:46 UTCEPSS rescore
  23. 2026-07-12 05:46 UTCEPSS rescore
  24. 2026-07-11 08:27 UTCEPSS rescore
  25. 2026-07-11 08:26 UTCEPSS rescore
Show 70 more
  1. 2026-07-09 19:09 UTCEPSS rescore
  2. 2026-07-08 15:14 UTCEPSS rescore
  3. 2026-07-07 13:45 UTCEPSS rescore
  4. 2026-07-07 05:51 UTCOSV refresh
  5. 2026-07-06 16:26 UTCEPSS rescore
  6. 2026-07-06 02:22 UTCEPSS rescore
  7. 2026-07-06 02:22 UTCEPSS rescore
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 06:30 UTCEPSS rescore
  10. 2026-07-01 15:06 UTCEPSS rescore
  11. 2026-06-30 23:21 UTCEPSS rescore
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  13. 2026-06-29 14:06 UTCEPSS rescore
  14. 2026-06-28 14:07 UTCEPSS rescore
  15. 2026-06-28 14:07 UTCEPSS rescore
  16. 2026-06-28 04:55 UTCEPSS rescore
  17. 2026-06-28 04:55 UTCEPSS rescore
  18. 2026-06-27 03:08 UTCEPSS rescore
  19. 2026-06-27 03:08 UTCEPSS rescore
  20. 2026-06-25 13:49 UTCEPSS rescore
  21. 2026-06-25 13:49 UTCEPSS rescore
  22. 2026-06-24 14:04 UTCEPSS rescore
  23. 2026-06-24 14:04 UTCEPSS rescore
  24. 2026-06-23 21:32 UTCEPSS rescore
  25. 2026-06-23 21:32 UTCEPSS rescore
  26. 2026-06-22 14:25 UTCEPSS rescore
  27. 2026-06-22 14:25 UTCEPSS rescore
  28. 2026-06-21 14:56 UTCEPSS rescore
  29. 2026-06-21 14:56 UTCEPSS rescore
  30. 2026-06-21 01:59 UTCEPSS rescore
  31. 2026-06-21 01:59 UTCEPSS rescore
  32. 2026-06-19 19:25 UTCEPSS rescore
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  34. 2026-06-18 17:52 UTCEPSS rescore
  35. 2026-06-18 17:52 UTCEPSS rescore
  36. 2026-06-18 17:05 UTCOSV refresh
  37. 2026-06-17 17:52 UTCEPSS rescore
  38. 2026-06-16 17:52 UTCEPSS rescore
  39. 2026-06-16 17:52 UTCEPSS rescore
  40. 2026-06-15 17:48 UTCEPSS rescore
  41. 2026-06-14 23:17 UTCEPSS rescore
  42. 2026-06-13 22:59 UTCEPSS rescore
  43. 2026-06-12 23:11 UTCEPSS rescore
  44. 2026-06-11 13:59 UTCEPSS rescore
  45. 2026-06-10 22:18 UTCEPSS rescore
  46. 2026-06-10 13:22 UTCEPSS rescore
  47. 2026-06-08 14:16 UTCEPSS rescore
  48. 2026-06-08 14:16 UTCEPSS rescore
  49. 2026-06-07 15:24 UTCEPSS rescore
  50. 2026-06-07 15:24 UTCEPSS rescore
  51. 2026-06-06 13:47 UTCEPSS rescore
  52. 2026-06-06 13:47 UTCEPSS rescore
  53. 2026-06-05 22:46 UTCEPSS rescore
  54. 2026-06-05 22:46 UTCEPSS rescore
  55. 2026-06-05 06:10 UTCEPSS rescore
  56. 2026-06-05 06:10 UTCEPSS rescore
  57. 2026-06-04 13:11 UTCEPSS rescore
  58. 2026-06-04 13:11 UTCEPSS rescore
  59. 2026-06-02 20:12 UTCEPSS rescore
  60. 2026-06-02 20:12 UTCEPSS rescore
  61. 2026-06-01 13:51 UTCEPSS rescore
  62. 2026-06-01 13:51 UTCEPSS rescore
  63. 2026-05-31 22:30 UTCEPSS rescore
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  65. 2026-05-31 00:16 UTCEPSS rescore
  66. 2026-05-31 00:16 UTCEPSS rescore
  67. 2026-05-30 08:22 UTCEG score recompute
  68. 2026-05-30 08:22 UTCVendor advisory
  69. 2026-05-30 08:22 UTCGHSA enrichment
  70. 2026-05-29 13:44 UTCEPSS rescore

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2025-21971?
CVE-2025-21971 is a medium vulnerability published on April 1, 2025. In the Linux kernel, the following vulnerability has been resolved: netsched: Prevent creation of classes with TCH_ROOT The function qdisctreereducebacklog() uses TCH_ROOT as a termination condition when traversing up the qdisc tree to update parent backlog counters. However, if a class is created…
When was CVE-2025-21971 disclosed?
CVE-2025-21971 was first published in the National Vulnerability Database on April 1, 2025, with the most recent update on November 3, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-21971 actively exploited?
CVE-2025-21971 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 9.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-21971?
CVE-2025-21971 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-21971?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-21971, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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