CVE-2026-89793

HIGHPre-NVD 7.87.8—
EchelonGraph scoreHIGH confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-09-16. A secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
7.8EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 7.8Exploit: 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:

ublk: clear VM_MAYWRITE on read-only ublk char device mmap

ublk_ch_mmap() rejects mmap requests with VM_WRITE set, but never clears VM_MAYWRITE on the resulting read-only mapping. This allows a userspace daemon to mmap the per-queue command buffer PROT_READ, then upgrade it to PROT_WRITE via mprotect(), since VM_MAYWRITE was never cleared.

The command buffer holds struct ublksrv_io_desc entries that are kernel-written ABI; a writable mapping lets an unprivileged daemon process corrupt fields such as addr, op_flags, nr_sectors, and start_sector.

Same bug class as the drm/panthor and drm/vc4 VM_MAYWRITE fixes, and the 2026-08-13 ptp/vmclock fix (a5edadbae57e).

Verified via mprotect() PoC: before the fix, a PROT_READ mapping can be upgraded to PROT_READ|PROT_WRITE and a write into the command buffer corrupts io_desc fields (confirmed under KASAN). After the fix, mprotect() returns -EACCES.

CVSS v3
7.8
EG Score
7.8HIGHhigh confidence
EG Risk
40
EG Risk 40/100CISA 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
Severity78% × 45%
Exploitation0% × 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
0.2%
EPSS %ILE
6th
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 partial (CVSS below 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

October 5, 2026

Advisory Details (5)

Auto-updated Sep 16, 2026
No patch confirmed yet.
generic

ublk: clear VM_MAYWRITE on read-only ublk char device mmap - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/fa5e1bc673ca59722608af67b27e65dba0c97926
generic

ublk: clear VM_MAYWRITE on read-only ublk char device mmap - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e373c1acdbcf88cec533ece9f589020adaed0a78
generic

ublk: clear VM_MAYWRITE on read-only ublk char device mmap - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/be41733c24be58e2a1ef718c80fafdfb98a40d5e
generic

ublk: clear VM_MAYWRITE on read-only ublk char device mmap - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/6e2b571b0a54755b06e092501913e1dfefe75d6c
generic

ublk: clear VM_MAYWRITE on read-only ublk char device mmap - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5befd06a72216869b607cf7724a4f16c6a2d3999

Vendor Advisories for CVE-2026-89793(2)

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

Affected Packages

(4 across 3 ecosystems)
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 7.2~rc7-1~exp1 (360 versions)
  • every version on: no fix on record
—
linux-6.126.12.100-1~deb12u1, 6.12.101-1~deb12u1, 6.12.107-1~deb12u1
  • every version up to 6.12.111-1~deb12u1: fixed in 6.12.111-1~deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 6.12.96-1 (35 versions)
  • every version up to 6.12.111-1: fixed in 6.12.111-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.2~rc7-1~exp1 (179 versions)
  • every version up to 7.2.6-1: fixed in 7.2.6-1
—

Data Freshness Timeline

(refreshed 42× in last 7d / 113× 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 113 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-89793?
CVE-2026-89793 is a high vulnerability published on September 16, 2026. In the Linux kernel, the following vulnerability has been resolved: ublk: clear VM_MAYWRITE on read-only ublk char device mmap ublkchmmap() rejects mmap requests with VM_WRITE set, but never clears VM_MAYWRITE on the resulting read-only mapping. This allows a userspace daemon to mmap the per-queue…
When was CVE-2026-89793 disclosed?
CVE-2026-89793 was first published on September 16, 2026, with the most recent update on October 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-89793 actively exploited?
CVE-2026-89793 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (6th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-89793?
CVE-2026-89793 has a CVSS base score of 7.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-89793?
No fix for CVE-2026-89793 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-2026-89793 are linked in the Vendor Advisories panel on this page.

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