nfsd: fix possible fh_compose of wrong dentry in nfsd4_create_file()
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix possible fh_compose of wrong dentry in nfsd4_create_file() dentry_create() can hypothetically provide a different dentry than the one passed in. This could happen, for example, if the exported filesystem is NFS, and the server returned to OPEN a filehandle which matched a directory that was already in the dcache. Clearly this would not be expected! If this were to happen the dentry (child) that was already stored in resfhp could be freed and later dereferenced. We shouldn't call fh_compose() until we are certain that we have the final dentry, so this patch moved the fh_compose() call to two places: one for the case where the target already exists, and one after dentry_create() where it was created.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 7.2.4, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet |
Not affected: 5 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89677
- 2026-10-03 Alias added: GHSA-rgqw-p3pf-j5p9
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-29 CVSS score changed · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
More Linux vulnerabilities
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Sources
- CVE-2026-89677 · CVE Program
- CVE-2026-89677 · NVD
- FIRST EPSS
- GHSA-rgqw-p3pf-j5p9 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89677 · Red Hat security data · CC BY 4.0
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