CVE-2026-89678: Linux kernel · nfsd: fix partial-write detection in nfsd_direct_write
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.5 High.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available and has been applied in the specified Linux kernel versions. Users should upgrade to the patched versions listed to resolve this issue. No additional mitigation steps are indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's nfsd_direct_write function causes incorrect detection of partial writes. The function fails to properly detect short writes between 50% and 99% of a segment, leading to writing data at incorrect file offsets and over-reporting write counts to NFS clients. This issue has been resolved in specific Linux kernel versions.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89678 (opens in a new tab)
- git.kernel.org/stable/c/250ec14932d5cfe102f68a57892bb566eee7f83e (opens in a new tab)
- git.kernel.org/stable/c/fa6590dfd16ab55f03b658b079072ace3504825e (opens in a new tab)
- ubuntu.com/security/CVE-2026-89678 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89678 (opens in a new tab)
- git.kernel.org/linus/250ec14932d5cfe102f68a57892bb566eee7f83e (opens in a new tab)