CVE-2025-21703

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2025-02-18. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

A fix is available — apply it.

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

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()

qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
21%
KEV
Not listed

Published

February 18, 2025

Last Modified

August 5, 2026

Advisory Details (8)

Auto-updated Aug 5, 2026
No patch confirmed yet.
generic

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/638ba5089324796c2ee49af10427459c2de35f71
generic

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/839ecc583fa00fab785fde1c85a326743657fd32
generic

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/6312555249082d6d8cc5321ff725df05482d8b83
generic

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5
generic

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/7b79ca9a1de6a428d486ff52fb3d602321c08f55
generic

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/98a2c685293aae122f688cde11d9334dddc5d207
generic

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/7f31d74fcc556a9166b1bb20515542de7bb939d1
generic

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c

Vendor Advisories for CVE-2025-21703(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(17)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-24.04-edge (6.11.0-24.24+1) @ oracular2026-05-30ubuntu
ubuntulinux-tools-azure (6.11.0-1013.13) @ oracular2026-05-30ubuntu
ubuntulinux-virtual-hwe-20.04-edge (5.15.0.138.134) @ jammy2026-05-30ubuntu
ubuntulinux-tools-gcp-fips (5.15.0.1081.71) @ jammy2026-05-30ubuntu
ubuntulinux-tools-realtime (5.15.0.1082.86) @ jammy2026-05-30ubuntu
ubuntulinux-tools-oracle-edge (5.15.0.1079.85~20.04.1) @ focal2026-05-30ubuntu
ubuntulinux-tools-aws-fips (5.4.0.1144.91) @ focal2026-05-30ubuntu
ubuntulinux-tools-azure-fips (5.15.0.1087.72) @ jammy2026-05-30ubuntu
ubuntulinux-virtual-hwe-18.04-edge (5.4.0.214.207) @ focal2026-05-30ubuntu
ubuntulinux-tools-gcp-edge (5.4.0.1147.156~18.04.1) @ bionic2026-05-30ubuntu
ubuntulinux-tools-gcp-fips (5.4.0.1147.89) @ focal2026-05-30ubuntu
ubuntulinux-tools-intel-iotg-edge (5.15.0.1077.83~20.04.1) @ focal2026-05-30ubuntu
ubuntulinux-tools-gcp-edge (5.15.0.1081.90~20.04.1) @ focal2026-05-30ubuntu
ubuntulinux-tools-aws-edge (5.15.0.1082.89~20.04.1) @ focal2026-05-30ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.4.0-1062 (5.4.0-1062.66) @ focal2026-05-30ubuntu
ubuntulinux-xilinx-zynqmp-tools-host (5.15.0-1046.50) @ jammy2026-05-30ubuntu
linuxKernel @ 5.4.291—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.

Additional Vendor Advisories

(16)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 41× 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.

Showing the most recent 100 of 111 total refreshes for this CVE.

  1. 2026-08-07 16:26 UTCEPSS rescore
  2. 2026-08-06 13:46 UTCEPSS rescore
  3. 2026-08-05 19:16 UTCEPSS rescore
  4. 2026-08-05 14:05 UTCEG score recompute
  5. 2026-08-05 14:05 UTCVendor advisory
  6. 2026-08-05 14:05 UTCGHSA enrichment
  7. 2026-08-04 15:09 UTCEPSS rescore
  8. 2026-08-04 10:37 UTCEPSS rescore
  9. 2026-08-02 02:25 UTCEPSS rescore
  10. 2026-08-01 04:15 UTCEPSS rescore
  11. 2026-07-30 16:27 UTCEPSS rescore
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  15. 2026-07-26 14:53 UTCEPSS rescore
  16. 2026-07-25 14:17 UTCEPSS rescore
  17. 2026-07-24 15:11 UTCOSV refresh
  18. 2026-07-24 14:17 UTCEPSS rescore
  19. 2026-07-23 14:17 UTCEPSS rescore
  20. 2026-07-23 02:50 UTCEG score recompute
  21. 2026-07-22 14:07 UTCEPSS rescore
  22. 2026-07-22 14:07 UTCEPSS rescore
  23. 2026-07-20 17:07 UTCEPSS rescore
  24. 2026-07-19 14:30 UTCEPSS rescore
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  1. 2026-07-19 02:28 UTCEPSS rescore
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  3. 2026-07-18 10:03 UTCEPSS rescore
  4. 2026-07-16 17:02 UTCEPSS rescore
  5. 2026-07-15 16:57 UTCEPSS rescore
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  7. 2026-07-15 01:59 UTCEPSS rescore
  8. 2026-07-13 22:29 UTCEPSS rescore
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  10. 2026-07-13 06:12 UTCEPSS rescore
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  12. 2026-07-12 05:46 UTCEPSS rescore
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  14. 2026-07-11 08:27 UTCEPSS rescore
  15. 2026-07-11 08:26 UTCEPSS rescore
  16. 2026-07-09 19:09 UTCEPSS rescore
  17. 2026-07-08 15:14 UTCEPSS rescore
  18. 2026-07-07 13:45 UTCEPSS rescore
  19. 2026-07-07 10:51 UTCOSV refresh
  20. 2026-07-06 16:26 UTCEPSS rescore
  21. 2026-07-06 02:22 UTCEPSS rescore
  22. 2026-07-06 02:22 UTCEPSS rescore
  23. 2026-07-05 02:30 UTCEPSS rescore
  24. 2026-07-04 06:30 UTCEPSS rescore
  25. 2026-07-01 15:06 UTCEPSS rescore
  26. 2026-06-30 23:21 UTCEPSS rescore
  27. 2026-06-30 23:21 UTCEPSS rescore
  28. 2026-06-29 14:06 UTCEPSS rescore
  29. 2026-06-28 14:07 UTCEPSS rescore
  30. 2026-06-28 14:07 UTCEPSS rescore
  31. 2026-06-28 04:55 UTCEPSS rescore
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  39. 2026-06-23 21:32 UTCEPSS rescore
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  41. 2026-06-22 14:25 UTCEPSS rescore
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  43. 2026-06-21 14:56 UTCEPSS rescore
  44. 2026-06-21 14:56 UTCEPSS rescore
  45. 2026-06-21 01:59 UTCEPSS rescore
  46. 2026-06-21 01:59 UTCEPSS rescore
  47. 2026-06-19 19:25 UTCEPSS rescore
  48. 2026-06-19 19:25 UTCEPSS rescore
  49. 2026-06-18 21:44 UTCOSV refresh
  50. 2026-06-18 17:52 UTCEPSS rescore
  51. 2026-06-18 17:52 UTCEPSS rescore
  52. 2026-06-17 17:52 UTCEPSS rescore
  53. 2026-06-16 17:52 UTCEPSS rescore
  54. 2026-06-16 17:52 UTCEPSS rescore
  55. 2026-06-15 17:48 UTCEPSS rescore
  56. 2026-06-14 23:17 UTCEPSS rescore
  57. 2026-06-13 22:59 UTCEPSS rescore
  58. 2026-06-12 23:11 UTCEPSS rescore
  59. 2026-06-11 13:59 UTCEPSS rescore
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  62. 2026-06-08 14:16 UTCEPSS rescore
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  64. 2026-06-07 15:24 UTCEPSS rescore
  65. 2026-06-07 15:24 UTCEPSS rescore
  66. 2026-06-06 13:47 UTCEPSS rescore
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  68. 2026-06-05 22:46 UTCEPSS rescore
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  70. 2026-06-05 06:10 UTCEPSS rescore
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  72. 2026-06-04 13:11 UTCEPSS rescore
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  74. 2026-06-02 20:12 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2025-21703?
CVE-2025-21703 is a high vulnerability published on February 18, 2025. In the Linux kernel, the following vulnerability has been resolved: netem: Update sch->q.qlen before qdisctreereduce_backlog() qdisctreereduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise…
When was CVE-2025-21703 disclosed?
CVE-2025-21703 was first published in the National Vulnerability Database on February 18, 2025, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-21703 actively exploited?
CVE-2025-21703 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 78.8% of all scored CVEs.
What is the CVSS score of CVE-2025-21703?
CVE-2025-21703 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2025-21703?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-21703, 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.

Dependency Blast Radius

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