CVE-2026-93811: ksmbd: Fix acl.sd_buf memory leak and invalid sd_size error handling

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-24 · updated 2026-10-03

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: Fix acl.sd_buf memory leak and invalid sd_size error handling 1. When ndr_decode_v4_ntacl() fails, the code jumped to free_n_data which only freed n.data, skipping kfree(acl.sd_buf) and leaking the buffer. Zero-initialize struct xattr_ntacl acl, reorder error labels to out_free to release acl.sd_buf on all error paths. 2. if (acl.sd_size < sizeof(struct smb_ntsd)) is true, original code returned success without freeing sd_buf and left stale *pntsd. Set rc = -EINVAL before jumping to out_free to return error code and free buffer.

Affected products

Linux kernel: from 5.15.62 before 5.15.222; from 5.18.18 before 5.19; from 5.19.2 before 5.20; 6.0 — fixed in 5.15.222, 5.19, 5.20, 7.2

How to fix

Upgrade to a fixed version: Linux kernel 5.15.222, 5.19, 5.20, 7.2. Check the vendor advisory for mitigations.

References

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