EUVD-2026-76611
GHSA-864v-pq9r-vg9w
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Decode occurs before auth checks (PR:N); network-reachable on standard NFS port; no confidentiality or integrity impact, only availability via memory exhaustion.
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
Lifecycle Timeline
6DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
nfsd: validate symlink target length in NFSv4 CREATE
nfsd4_decode_create() accepts an unbounded cr_datalen from the wire for NF4LNK symlink targets, allowing a client to force a kmalloc of up to the maximum RPC payload size (several MiB) per COMPOUND op that persists until compound teardown. The VFS rejects oversized targets with ENAMETOOLONG, but the allocation has already occurred.
Reject cr_datalen == 0 early with nfserr_inval and cr_datalen greater than NFS4_MAXPATHLEN (PATH_MAX) with nfserr_nametoolong to bound the allocation.
AnalysisAI
Memory exhaustion DoS in Linux kernel NFSv4 server (nfsd) allows any network-reachable client to force multi-MiB kernel heap allocations per COMPOUND operation. The flaw lies in nfsd4_decode_create(), which accepted an unbounded cr_datalen wire value for NF4LNK symlink targets without validation - allocating up to the full RPC payload size (several MiB) per request before the VFS eventually rejected the target with ENAMETOOLONG. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Requires network access to TCP/UDP port 2049 on a Linux host running the nfsd kernel module with NFSv4 support enabled (CONFIG_NFSD and CONFIG_NFSD_V4 compiled in and the nfsd service active). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score 7.5) is plausible for the raw bug: nfsd decodes the COMPOUND request - including allocating cr_datalen bytes - before authentication checks complete, so PR:N is defensible. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the upstream kernel fix available in stable releases 6.12.109, 6.18.50, 7.2.4, or 7.3-rc1, referencing the patch commits at https://git.kernel.org/stable/c/b24843ea3de1676b29902457b38507c95a80649b (6.12.x), https://git.kernel.org/stable/c/895a485cd3758031ef9993c0d53cf19ce8fb4ccc (6.18.x), https://git.kernel.org/stable/c/45ec115cbfecb4b3cfab7fca6f73d1b60696a25a (7.2.x), and https://git.kernel.org/stable/c/041f57056e5fb9c80adc088269322d2c61074406 (7.3-rc1). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all Linux systems running NFSv4 NFS servers (check for nfsd kernel module and NFS exports). …
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External POC / Exploit Code
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