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major vulnerability· requires attention

Linux kernel RCE in ksmbd affects widely deployed OS kernels and SMB servers; impactful across enterprises and infrastructure.

Systems

CVE-2026-89788

9.8
Critical
EPSS 0.65%Patch available

ksmbd use-after-free in smb2_tree_connect allows remote kernel compromise via SMB

exploited
No known exploitation not in CISA KEV as of our last sync
fix
Fixed in < 6.6, >= 7.2.6 and <= 7.2.*, >= 7.3-rc2 and <= *
likelihood
EPSS 0.65%top 49% of scored CVEs
Published 16 Sept 2026Analysed here 18 Sept 2026CVSS scored by the publisher (CNA)

do firstUpgrade to a fixed release: < 6.6, >= 7.2.6 and <= 7.2.*, >= 7.3-rc2 and <= *.

common questions

Is CVE-2026-89788 being exploited?

Not confirmed. CVE-2026-89788 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.65% probability of exploitation in the next 30 days.

How severe is CVE-2026-89788?

CVE-2026-89788 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-89788?

Yes. A fix has been recorded for CVE-2026-89788. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-89788 affect?

CVE-2026-89788 affects Linux kernel (ksmbd SMB server), Servers exposing SMB (port 445), Distributions shipping ksmbd. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2026-89788?

Apply vendor kernel updates or backported ksmbd patch; block/limit SMB exposure until patched.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
Linux kernel (ksmbd SMB server)Servers exposing SMB (port 445)Distributions shipping ksmbd
impact

Remote code execution or kernel crash via crafted SMB2 TREE_CONNECT; attacker can achieve kernel-level compromise or DoS on exposed SMB servers.

action required

Immediate action required

affected versions
Linux
  • affected>= 33b235a6e6ebe0f05f3586a71e8d281d00f71e2e and < 4e30fbd26e84efa2e5cbec4eb11e126ac0c79313
  • affected>= 33b235a6e6ebe0f05f3586a71e8d281d00f71e2e and < b5ec6c462aab1062cf5d1e667ba7c6442f737055
  • affecteddd45db4d9bbc8f122a9b4db5ce94ae29fcf03d3c
  • affected7b58ee8d0b91359554cf219cd4f33872ea2afd66
  • affected>= 5.15.145 and < 5.16
  • affected>= 6.1.71 and < 6.2
  • affected6.6
vendor says fixed in< 6.6, >= 7.2.6 and <= 7.2.*, >= 7.3-rc2 and <= *

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

timeline

  1. 16 Sept 2026Published
  2. 18 Sept 2026Analysed by vulneraibility.com · 2 days later
  3. 30 Oct 2026CVE record last updated · 42 days later
how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
NVDCVE.orgCVE DetailsSource
5 references in the CVE record: 5 links

sources

  • CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
  • NVD: CVSS and CPE data
  • FIRST EPSS: exploit probability and percentile
  • Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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