CVE-2026-89788

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-16. A secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 9.8Exploit: None knownExposed services: Not assessed

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

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

ksmbd: fix tree connection use-after-free in smb2_tree_connect()

ksmbd_tree_conn_connect() publishes a new tree connection in sess->tree_conns with a single reference and returns its pointer to smb2_tree_connect(). The handler continues to initialize the object and build the response after publication. A concurrent session logoff can erase the connection and drop that reference, freeing the object while the handler still uses it.

BUG: KASAN: slab-use-after-free in smb2_tree_connect+0xe3d/0xf90 smb2_tree_connect (fs/smb/server/smb2pdu.c:2872) handle_ksmbd_work process_one_work worker_thread kthread

After xa_store() succeeds, take a second reference before releasing tree_conns_lock. The original reference belongs to the xarray entry and the second belongs to the creating smb2_tree_connect() handler.

Keep the references balanced in every path:

  • On normal exit or an error after publication, smb2_tree_connect()
drops its creator reference. Error cleanup also calls ksmbd_tree_conn_disconnect(), which drops the xarray reference only if it removes the exact entry.
  • SMB2 TREE_DISCONNECT uses the same helper to remove the entry and drop
its xarray reference. The request's existing lookup reference remains owned by the request and is released by the existing cleanup.
  • Session LOGOFF removes each entry and drops its xarray reference. If
it wins the race, later cleanup sees that the entry is gone and does not drop that reference again.

To enforce this ownership, claim the disconnected state and erase the exact entry atomically under tree_conns_lock. This guarantees one drop for the xarray reference and one drop by each in-flight user, regardless of which teardown path wins. If logoff removes the entry before initialization completes, fail the connect instead of marking the detached object TREE_CONNECTED.

CVSS v3
9.8
EG Score
9.8CRITICALhigh confidence
EG Risk
49
EG Risk 49/100CISA SSVC

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
Severity98% × 45%
Exploitation1% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track* or Attend at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.6%
EPSS %ILE
44th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* or Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact total (CVSS ≥ 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 16, 2026

Last Modified

September 16, 2026

Advisory Details (2)

Auto-updated Sep 30, 2026
No patch confirmed yet.
generic

ksmbd: fix tree connection use-after-free in smb2_tree_connect() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b5ec6c462aab1062cf5d1e667ba7c6442f737055
generic

ksmbd: fix tree connection use-after-free in smb2_tree_connect() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4e30fbd26e84efa2e5cbec4eb11e126ac0c79313

Vendor Advisories for CVE-2026-89788(2)

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 rangeFix by version rangeDependents
linux6.1.106-1 ... 7.2~rc7-1~exp1 (358 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.2~rc7-1~exp1 (181 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.2~rc7-1~exp1 (178 versions)
  • every version up to 7.2.6-1: fixed in 7.2.6-1
—

Data Freshness Timeline

(refreshed 101× in last 7d / 274× 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 274 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-89788?
CVE-2026-89788 is a critical vulnerability published on September 16, 2026. In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix tree connection use-after-free in smb2treeconnect() ksmbdtreeconn_connect() publishes a new tree connection in sess->tree_conns with a single reference and returns its pointer to smb2treeconnect(). The handler continues…
When was CVE-2026-89788 disclosed?
CVE-2026-89788 was first published on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-89788 actively exploited?
CVE-2026-89788 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (44th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-89788?
CVE-2026-89788 has a CVSS base score of 9.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-89788?
No fix for CVE-2026-89788 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-89788 are linked in the Vendor Advisories panel on this page.

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