CVE-2026-89787

UNRATEDCVSS · not yet scoredTrending — 4 sources updated this week
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EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS v2: —Exploit: 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:

ext4: check dir entry fits before reading the hash trailer in ext4_search_dir()

For casefolded encrypted directories ext4 stores an 8-byte hash trailer after the name (EXT4_DIRENT_HASHES()), at an offset derived from de->name_len. On the sb_no_casefold_compat_fallback() path ext4_match() reads that trailer, but ext4_search_dir()'s by-hand pre-check only tests de->name + de->name_len <= dlimit, which proves the name fits, not the rounded trailer. A crafted entry whose name ends at the block boundary passes the check while EXT4_DIRENT_HASHES(de) lands past the block end, so ext4_match() reads out of bounds on an ordinary lookup. KASAN reports it as a use-after-free when the page after the directory block holds a freed object:

BUG: KASAN: use-after-free in ext4_match (fs/ext4/namei.c:1435) Read of size 4 at addr ffff888010458000 by task exploit Call Trace: ext4_match (fs/ext4/namei.c:1435) ext4_search_dir (fs/ext4/namei.c:1470) __ext4_find_entry (fs/ext4/namei.c:1268 fs/ext4/namei.c:1632) ext4_lookup (fs/ext4/namei.c:1703 fs/ext4/namei.c:1769) ... filename_lookup (fs/namei.c:2842) vfs_statx (fs/stat.c:353) __do_sys_newfstatat (fs/stat.c:538) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)

Require, for hash-in-dirent directories, that the whole entry including the rounded trailer fits before calling ext4_match(). This is the same bound ext4_check_dir_entry() already enforces via ext4_dir_rec_len(), so no well-formed entry is rejected. The other caller, ext4_find_dest_de(), runs ext4_check_dir_entry() first and is unaffected.

CVSS v3
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EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
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EG Risk
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EPSS PROB
0.2%
EPSS %ILE
9th
KEV
Not listed

Published

September 16, 2026

Last Modified

September 16, 2026

References (7)

Vendor Advisories for CVE-2026-89787(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
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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
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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
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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
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Data Freshness Timeline

(refreshed 10× in last 7d / 29× 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.

  1. 2026-10-04 23:22 UTCEPSS rescore
  2. 2026-10-02 20:43 UTCVendor advisory
  3. 2026-10-02 20:43 UTCGHSA enrichment
  4. 2026-10-01 19:51 UTCEPSS rescore
  5. 2026-09-30 15:04 UTCEPSS rescore
  6. 2026-09-29 13:30 UTCEG score recompute
  7. 2026-09-29 13:30 UTCVendor advisory
  8. 2026-09-29 13:30 UTCGHSA enrichment
  9. 2026-09-28 13:52 UTCEPSS rescore
  10. 2026-09-28 13:52 UTCEPSS rescore
  11. 2026-09-27 13:49 UTCEPSS rescore
  12. 2026-09-26 15:59 UTCEPSS rescore
  13. 2026-09-26 06:34 UTCVendor advisory
  14. 2026-09-26 06:33 UTCGHSA enrichment
  15. 2026-09-24 14:04 UTCEPSS rescore
  16. 2026-09-23 17:54 UTCEPSS rescore
  17. 2026-09-22 23:34 UTCVendor advisory
  18. 2026-09-22 23:34 UTCGHSA enrichment
  19. 2026-09-21 21:09 UTCEPSS rescore
  20. 2026-09-20 20:16 UTCEPSS rescore
  21. 2026-09-19 16:26 UTCEG score recompute
  22. 2026-09-19 16:26 UTCVendor advisory
  23. 2026-09-19 16:26 UTCGHSA enrichment
  24. 2026-09-18 19:28 UTCEPSS rescore
  25. 2026-09-17 19:32 UTCEPSS rescore
Show 4 more
  1. 2026-09-16 14:09 UTCEPSS rescore
  2. 2026-09-16 09:29 UTCNVD update
  3. 2026-09-16 08:52 UTCEG score recompute
  4. 2026-09-16 08:51 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-89787?
CVE-2026-89787 is a publicly disclosed vulnerability published on September 16, 2026. In the Linux kernel, the following vulnerability has been resolved: ext4: check dir entry fits before reading the hash trailer in ext4searchdir() For casefolded encrypted directories ext4 stores an 8-byte hash trailer after the name (EXT4DIRENTHASHES()), at an offset derived from de->namelen. On…
When was CVE-2026-89787 disclosed?
CVE-2026-89787 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-2026-89787 actively exploited?
CVE-2026-89787 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (9th percentile of EPSS-scored CVEs).
How do I remediate CVE-2026-89787?
No fix for CVE-2026-89787 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-2026-89787 are linked in the Vendor Advisories panel on this page.

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