In the Linux kernel, the following vulnerability has been resolved:
nfsd: fix refcount leak in nfsd_set_fh_dentry()
nfsd exports a "pseudo root filesystem" which is used by NFSv4 to find the various exported filesystems using LOOKUP requests from a known root filehandle. NFSv3 uses the MOUNT protocol to find those exported filesystems and so is not given access to the pseudo root filesystem.
If a v3 (or v2) client uses a filehandle from that filesystem, nfsd_set_fh_dentry() will report an error, but still stores the export in "struct svc_fh" even though it also drops the reference (exp_put()). This means that when fh_put() is called an extra reference will be dropped which can lead to use-after-free and possible denial of service.
Normal NFS usage will not provide a pseudo-root filehandle to a v3 client. This bug can only be triggered by the client synthesising an incorrect filehandle.
To fix this we move the assignments to the svc_fh later, after all possible error cases have been detected.
CVSS Details
- CVSS 3.1 Base Score: 9.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel6.12-headersUpgrade kernel6.12-develUpgrade kernel6.12-tools-debuginfoUpgrade perf6.12-debuginfoUpgrade python3-perf6.12Upgrade kernel-livepatch-6.12.63-84.121Upgrade python3-perf6.12-debuginfoUpgrade kernel6.12-debuginfoUpgrade kernel6.12Upgrade kernel6.12-libbpf-debuginfoUpgrade perf6.12Upgrade kernel6.12-modules-extraUpgrade kernel6.12-toolsUpgrade bpftool6.12-debuginfoUpgrade kernel6.12-tools-develUpgrade kernel6.12-libbpf-develUpgrade kernel6.12-modules-extra-commonUpgrade bpftool6.12Upgrade kernel6.12-debuginfo-common-aarch64Upgrade kernel6.12-libbpfUpgrade kernel6.12-debuginfo-common-x86_64Upgrade kernel6.12-libbpf-static | Feb 20, 2026 | Nov 24, 2025 |
| Debian | — | Upgrade linux | Jul 23, 2026 | Jul 23, 2026 |
| Oracle_linux | — | Upgrade kernel-uek | Jan 15, 2026 | Nov 24, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Nov 24, 2025 |
| Ubuntu | — | Upgrade linux-image-aws-64kUpgrade linux-image-6.17.0-1008-azureUpgrade linux-image-6.17.0-1006-realtimeUpgrade linux-image-6.17.0-1007-aws-64kUpgrade linux-image-realtimeUpgrade linux-image-aws-6.17Upgrade linux-image-6.17.0-14-generic-64kUpgrade linux-image-gcpUpgrade linux-image-virtualUpgrade linux-image-oracle-64kUpgrade linux-image-generic-6.17Upgrade linux-image-generic-64kUpgrade linux-image-realtime-6.17Upgrade linux-image-virtual-6.17Upgrade linux-image-gcp-6.17Upgrade linux-image-raspi-6.17Upgrade linux-image-6.17.0-1007-oracleUpgrade linux-image-awsUpgrade linux-image-6.17.0-1011-oemUpgrade linux-image-6.17.0-1007-gcpUpgrade linux-image-oracleUpgrade linux-image-gcp-64kUpgrade linux-image-aws-64k-6.17Upgrade linux-image-6.17.0-1007-awsUpgrade linux-image-generic-64k-6.17Upgrade linux-image-gcp-64k-6.17Upgrade linux-image-azure-6.17Upgrade linux-image-oracle-64k-6.17Upgrade linux-image-6.17.0-1008-raspiUpgrade linux-image-genericUpgrade linux-image-raspiUpgrade linux-image-azureUpgrade linux-image-6.17.0-14-genericUpgrade linux-image-oracle-6.17Upgrade linux-image-6.17.0-1007-oracle-64kUpgrade linux-image-6.17.0-1007-gcp-64kUpgrade linux-image-oem-6.17 | Feb 13, 2026 | Feb 12, 2026 |
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