CVE-2026-97555
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)
Executive briefing
A structured intelligence assessment has not yet been generated. The source description is shown above. The background enrichment worker will retry this record.
Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:Not supplied
No CVSS vector is currently available in the source record.
Technical explanation & impact
Technical root-cause details are not available in the current source record.
Assess the impact using the published CVSS metrics and the affected vendor component.
Affected products and versions
NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.
Vendor advisories, patches & exploit references
No external references are currently supplied in the CVE record.