CVE-2026-63867

HIGHPre-NVD 8.28.2—
EchelonGraph scoreMEDIUM confidence

Score 8.2 from GitHub Security Advisory (severity: HIGH) published 2026-07-19. the CNA's CVSS baseline 8.2; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:linux, epss, ghsa
Trending — 3 sources updated this week
8.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.2Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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

mptcp: close TOCTOU race while computing rcv_wnd

The MPTCP output path access locklessly the MPTCP-level ack_seq in multiple times, using possibly different values for the data_ack in the DSS option and to compute the announced rcv wnd for the same packet.

Refactor the cote to avoid inconsistencies which may confuse the peer. Also ensure that the MPTCP level rcv wnd is updated only when the egress packet actually contains a DSS ack.

CVSS v3
8.2
EG Score
8.2(medium)
EG Risk
42(Track)
EG Risk 42/100SSVC: 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
Severity82% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
46%
KEV
Not listed

Published

July 19, 2026

Last Modified

August 5, 2026

Advisory Details (7)

Auto-updated Jul 21, 2026
No patch confirmed yet.
generic

mptcp: close TOCTOU race while computing rcv_wnd - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f
generic

mptcp: close TOCTOU race while computing rcv_wnd - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510
generic

mptcp: close TOCTOU race while computing rcv_wnd - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43
generic

mptcp: close TOCTOU race while computing rcv_wnd - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45
generic

mptcp: close TOCTOU race while computing rcv_wnd - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497
generic

mptcp: close TOCTOU race while computing rcv_wnd - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef
generic

mptcp: close TOCTOU race while computing rcv_wnd - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8

Vendor Advisories for CVE-2026-63867(1)

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

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (53 versions)6.1.176-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.94-1~bpo12+1 (27 versions)6.12.94-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.0.9-1~bpo13+1 (142 versions)7.0.13-1—

Data Freshness Timeline

(refreshed 23× in last 7d / 110× 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 240 total refreshes for this CVE.

  1. 2026-08-30 03:00 UTCEG score recompute
  2. 2026-08-30 03:00 UTCGHSA enrichment
  3. 2026-08-30 01:22 UTCEPSS rescore
  4. 2026-08-28 21:42 UTCEPSS rescore
  5. 2026-08-28 01:44 UTCEG score recompute
  6. 2026-08-28 01:44 UTCGHSA enrichment
  7. 2026-08-27 14:25 UTCEPSS rescore
  8. 2026-08-27 13:14 UTCGHSA enrichment
  9. 2026-08-27 01:07 UTCEG score recompute
  10. 2026-08-27 01:07 UTCGHSA enrichment
  11. 2026-08-26 14:46 UTCEPSS rescore
  12. 2026-08-26 12:58 UTCGHSA enrichment
  13. 2026-08-26 00:52 UTCEG score recompute
  14. 2026-08-26 00:52 UTCGHSA enrichment
  15. 2026-08-25 13:49 UTCEPSS rescore
  16. 2026-08-25 12:47 UTCGHSA enrichment
  17. 2026-08-25 00:41 UTCEG score recompute
  18. 2026-08-25 00:41 UTCGHSA enrichment
  19. 2026-08-24 12:32 UTCEG score recompute
  20. 2026-08-24 12:32 UTCGHSA enrichment
  21. 2026-08-24 00:27 UTCGHSA enrichment
  22. 2026-08-23 12:21 UTCEG score recompute
  23. 2026-08-23 12:21 UTCGHSA enrichment
  24. 2026-08-23 00:19 UTCEPSS rescore
  25. 2026-08-23 00:16 UTCGHSA enrichment
Show 75 more
  1. 2026-08-22 12:10 UTCGHSA enrichment
  2. 2026-08-21 23:51 UTCEG score recompute
  3. 2026-08-21 23:51 UTCGHSA enrichment
  4. 2026-08-21 23:49 UTCEPSS rescore
  5. 2026-08-21 11:44 UTCGHSA enrichment
  6. 2026-08-20 23:23 UTCEG score recompute
  7. 2026-08-20 23:23 UTCGHSA enrichment
  8. 2026-08-20 22:55 UTCEPSS rescore
  9. 2026-08-20 11:17 UTCGHSA enrichment
  10. 2026-08-19 23:12 UTCEG score recompute
  11. 2026-08-19 23:12 UTCGHSA enrichment
  12. 2026-08-19 17:04 UTCEPSS rescore
  13. 2026-08-19 07:56 UTCGHSA enrichment
  14. 2026-08-18 19:51 UTCEG score recompute
  15. 2026-08-18 19:50 UTCGHSA enrichment
  16. 2026-08-18 13:48 UTCEPSS rescore
  17. 2026-08-18 03:50 UTCGHSA enrichment
  18. 2026-08-17 15:43 UTCEG score recompute
  19. 2026-08-17 15:43 UTCGHSA enrichment
  20. 2026-08-17 13:47 UTCEPSS rescore
  21. 2026-08-17 03:38 UTCGHSA enrichment
  22. 2026-08-16 15:32 UTCEG score recompute
  23. 2026-08-16 15:32 UTCGHSA enrichment
  24. 2026-08-16 14:56 UTCEPSS rescore
  25. 2026-08-16 03:27 UTCEG score recompute
  26. 2026-08-16 03:27 UTCGHSA enrichment
  27. 2026-08-15 15:21 UTCGHSA enrichment
  28. 2026-08-15 03:15 UTCEG score recompute
  29. 2026-08-15 03:15 UTCGHSA enrichment
  30. 2026-08-15 01:30 UTCEPSS rescore
  31. 2026-08-14 15:09 UTCGHSA enrichment
  32. 2026-08-14 03:04 UTCEG score recompute
  33. 2026-08-14 03:04 UTCGHSA enrichment
  34. 2026-08-13 22:00 UTCEPSS rescore
  35. 2026-08-13 14:58 UTCGHSA enrichment
  36. 2026-08-13 02:52 UTCGHSA enrichment
  37. 2026-08-12 14:47 UTCEG score recompute
  38. 2026-08-12 14:47 UTCGHSA enrichment
  39. 2026-08-12 13:51 UTCEPSS rescore
  40. 2026-08-12 02:41 UTCGHSA enrichment
  41. 2026-08-11 14:35 UTCEG score recompute
  42. 2026-08-11 14:35 UTCGHSA enrichment
  43. 2026-08-11 02:30 UTCEG score recompute
  44. 2026-08-11 02:29 UTCGHSA enrichment
  45. 2026-08-11 00:00 UTCEPSS rescore
  46. 2026-08-10 14:24 UTCGHSA enrichment
  47. 2026-08-10 02:19 UTCGHSA enrichment
  48. 2026-08-09 14:13 UTCEG score recompute
  49. 2026-08-09 14:13 UTCGHSA enrichment
  50. 2026-08-09 13:47 UTCEPSS rescore
  51. 2026-08-09 02:08 UTCEG score recompute
  52. 2026-08-09 02:08 UTCGHSA enrichment
  53. 2026-08-08 16:37 UTCEPSS rescore
  54. 2026-08-08 14:03 UTCGHSA enrichment
  55. 2026-08-08 01:57 UTCEG score recompute
  56. 2026-08-08 01:57 UTCGHSA enrichment
  57. 2026-08-07 13:51 UTCGHSA enrichment
  58. 2026-08-07 01:46 UTCEG score recompute
  59. 2026-08-07 01:46 UTCGHSA enrichment
  60. 2026-08-06 13:47 UTCEPSS rescore
  61. 2026-08-06 13:41 UTCGHSA enrichment
  62. 2026-08-06 01:35 UTCEG score recompute
  63. 2026-08-06 01:35 UTCGHSA enrichment
  64. 2026-08-05 19:17 UTCEPSS rescore
  65. 2026-08-05 19:17 UTCEPSS rescore
  66. 2026-08-05 13:29 UTCEG score recompute
  67. 2026-08-05 13:29 UTCGHSA enrichment
  68. 2026-08-05 01:01 UTCEG score recompute
  69. 2026-08-05 01:01 UTCGHSA enrichment
  70. 2026-08-04 15:10 UTCEPSS rescore
  71. 2026-08-04 12:55 UTCEG score recompute
  72. 2026-08-04 12:55 UTCGHSA enrichment
  73. 2026-08-04 10:39 UTCEPSS rescore
  74. 2026-08-03 22:16 UTCGHSA enrichment
  75. 2026-08-03 10:10 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2026-63867?
CVE-2026-63867 is a high vulnerability published on July 19, 2026. In the Linux kernel, the following vulnerability has been resolved: mptcp: close TOCTOU race while computing rcv_wnd The MPTCP output path access locklessly the MPTCP-level ack_seq in multiple times, using possibly different values for the data_ack in the DSS option and to compute the announced rcv…
When was CVE-2026-63867 disclosed?
CVE-2026-63867 was first published in the National Vulnerability Database on July 19, 2026, 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-2026-63867 actively exploited?
CVE-2026-63867 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.3% of all scored CVEs.
What is the CVSS score of CVE-2026-63867?
CVE-2026-63867 has a CVSS v4.0 base score of 8.2 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-63867?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63867, 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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