Out-of-bounds Write Affecting kernel-rt-64k-debug-modules package, versions *


Severity

Recommended
medium

Based on CentOS security rating.

Threat Intelligence

EPSS
0.52% (43rd percentile)

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  • Snyk IDSNYK-CENTOS10-KERNELRT64KDEBUGMODULES-20239964
  • published29 Sept 2026
  • disclosed25 Sept 2026

Introduced: 25 Sep 2026

NewCVE-2026-97555  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-rt-64k-debug-modules.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-debug-modules package and not the kernel-rt-64k-debug-modules package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix heap overflow in DACL owner/group rewrite

When id_mode_to_cifs_acl rewrites an existing DACL, it allocates a buffer sized according to the on-disk DACL length reported by dacl_ptr->size. However, replace_sids_and_copy_aces may rewrite each ACE with a new owner/group SID obtained from the cifs.idmap upcall. Those SIDs can have up to SID_MAX_SUB_AUTHORITIES (15) sub-authorities, making each ACE up to 76 bytes (sizeof(struct smb_ace)).

If the original DACL contains short SIDs (e.g., 1 sub-authority) while the replacement SIDs are long, the rewritten ACEs overflow the allocation.

Fix this by always budgeting for worst-case SID expansion: allocate sizeof(struct smb_acl) plus num_aces * sizeof(struct smb_ace), which covers the smb_acl header and room for every ACE at maximum SID size. This replaces the previous split logic that used dacl_ptr->size for cifsacl mounts but num_aces * sizeof(struct smb_ace) for mode_from_sid mounts: both paths can trigger the same rewrite and need the same headroom.

KASAN reports this as: BUG: KASAN: slab-out-of-bounds in build_sec_desc+0x1e8a/0x2680 [cifs] Write of size 4 at addr ffff8881a5e25374 by task chown/5298 ... The buggy address is located 0 bytes to the right of allocated 884-byte region [ffff8881a5e25000, ffff8881a5e25374)

CVSS Base Scores

version 3.1