CVE-2026-89672: Linux Vulnerability (CVSS 9.1)

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: gate nfs2 setacl by argp->mask The NFSACL v2 SETACL path shares the decoder convention used by its v3 sibling: nfsaclsvc_decode_setaclargs() fills in argp->acl_access only when NFS_ACL is set in the request mask and argp->acl_default only when NFS_DFACL is set, leaving the other pointer NULL because the argument buffer is zeroed up to pc_argzero before decode. nfsacld_proc_setacl() then hands both pointers to set_posix_acl() unconditionally. set_posix_acl(idmap, dentry, type, NULL) is the VFS "remove this ACL type" operation, so an omitted arm is indistinguishable from an explicit request to delete that ACL. A SETACL carrying only NFS_ACL silently strips the directory's default ACL; mask=0 strips both. This is the same defect just fixed in nfsd3_proc_setacl(); apply the same remedy. Gate each set_posix_acl() call on its mask bit and initialize error to 0 so that a request with neither bit set leaves the on-disk ACLs untouched and returns success. The out_drop_lock path and the unconditional posix_acl_release() in nfsaclsvc_release_setacl() already tolerate the skipped arms.

Metrics

CVSS 3.1

9.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Probability

0.52%

42.8th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < 8e4422b05f410f95c51b68a0db4bf1d87f6d22f5; >= a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < e41d173d9dc735cecb15ab7aa63ecab09338f81b; >= a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < f951b22dbeec46f2e0fba81cb80d1b0c686b61eb; >= a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < 37eea38e7898538f0ec5f1eb8b18d8646e4be41c; >= a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < a3a7e20ed66d3f04d37883c398da8a113b430769
Linux	Linux	2.6.13

References

Timeline

Published: Sep 11, 2026
Last Modified: Sep 14, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-89672?

In the Linux kernel, the following vulnerability has been resolved: nfsd: gate nfs2 setacl by argp->mask The NFSACL v2 SETACL path shares the decoder convention used by its v3 sibling: nfsaclsvc_decode_setaclargs() fills in argp->acl_access only when NFS_ACL is set in the request mask and argp->acl_default only when NFS_DFACL is set, leaving the other pointer NULL because the argument buffer is zeroed up to pc_argzero before decode. nfsacld_proc_setacl() then hands both pointers to set_posix_acl() unconditionally. set_posix_acl(idmap, dentry, type, NULL) is the VFS "remove this ACL type" operation, so an omitted arm is indistinguishable from an explicit request to delete that ACL. A SETACL carrying only NFS_ACL silently strips the directory's default ACL; mask=0 strips both. This is the same defect just fixed in nfsd3_proc_setacl(); apply the same remedy. Gate each set_posix_acl() call on its mask bit and initialize error to 0 so that a request with neither bit set leaves the on-disk ACLs untouched and returns success. The out_drop_lock path and the unconditional posix_acl_release() in nfsaclsvc_release_setacl() already tolerate the skipped arms.

How severe is CVE-2026-89672?

CVE-2026-89672 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 0.52% probability of exploitation in the next 30 days.

How do I fix CVE-2026-89672?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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