CVE-2026-89778

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: 0.7%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:

isofs: fix out-of-bounds page array access on empty zisofs block

zisofs_uncompress_block()'s empty-block fast path returns pcount << PAGE_SHIFT, ignoring the incoming poffset, unlike the decompression path which returns bytes produced relative to poffset. zisofs_fill_pages() uses that return to advance its page cursor, so when the zisofs block size is below PAGE_SIZE and a sub-page block leaves poffset partway into a page, a following empty block over-counts and advances pages[] one element past its end, after which "if (poffset && *pages)" reads pages[1] out of bounds. rock.c only rejects a block-size shift > 17, so a crafted "ZF" Rock Ridge record can set it below PAGE_SHIFT; the bug is reached by an ordinary read() of a compressed file on such a mounted ISO9660 image.

Return the byte count relative to poffset and zero only [poffset, PAGE_SIZE) of the first page, matching the decompression path. The page-aligned case (poffset == 0) is unaffected.

BUG: KASAN: slab-out-of-bounds in zisofs_read_folio (fs/isofs/compress.c:290) Read of size 8 at addr ffff88800f5eac48 by task exploit/142 zisofs_read_folio (fs/isofs/compress.c:290) read_pages (mm/readahead.c:184) ... filemap_read (mm/filemap.c:2814) vfs_read (fs/read_write.c:574) __x64_sys_pread64 (fs/read_write.c:769) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) The buggy address is located 0 bytes to the right of the allocated 8-byte region in the kmalloc-8 cache

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
0.7%
EPSS %ILE
52nd
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 (7)

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

isofs: fix out-of-bounds page array access on empty zisofs block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f03425dcbe04aec3c27b9917e97d7d23a2908dda
generic

isofs: fix out-of-bounds page array access on empty zisofs block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/cd616aa0449a772a6956abf03358f0ff31720580
generic

isofs: fix out-of-bounds page array access on empty zisofs block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0a
generic

isofs: fix out-of-bounds page array access on empty zisofs block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9c6eace8d07e90f038c89eb3b756d65a7e259d48
generic

isofs: fix out-of-bounds page array access on empty zisofs block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8b994ac5778a725982fd6a8a3afcaa068d4a93e3
generic

isofs: fix out-of-bounds page array access on empty zisofs block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/85904076cece72ee3194646ad7ac8e6659d999aa
generic

isofs: fix out-of-bounds page array access on empty zisofs block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/68d4d3e78150c7ed7d1195af63ad1e6ace30c661

Vendor Advisories for CVE-2026-89778(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 88× in last 7d / 242× 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 242 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-89778?
CVE-2026-89778 is a critical vulnerability published on September 16, 2026. In the Linux kernel, the following vulnerability has been resolved: isofs: fix out-of-bounds page array access on empty zisofs block zisofsuncompressblock()'s empty-block fast path returns pcount << PAGE_SHIFT, ignoring the incoming poffset, unlike the decompression path which returns bytes…
When was CVE-2026-89778 disclosed?
CVE-2026-89778 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-2026-89778 actively exploited?
CVE-2026-89778 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (52nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-89778?
CVE-2026-89778 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-2026-89778?
No fix for CVE-2026-89778 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-2026-89778 are linked in the Vendor Advisories panel on this page.

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