ksmbd: use check_add_overflow() to prevent u16 DACL size overflow
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: use check_add_overflow() to prevent u16 DACL size overflow set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes in u16 variables. When a file has many POSIX ACL entries, the accumulated size can wrap past 65535, causing the pointer arithmetic (char *)pndace + *size to land within already-written ACEs. Subsequent writes then overwrite earlier entries, and pndacl->size gets a truncated value. Use check_add_overflow() at each accumulation point to detect the wrap before it corrupts the buffer, consistent with existing check_mul_overflow() usage elsewhere in smbacl.c.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 5.15 and later | 6.1.175, 6.6.136, 6.12.84, 6.18.25, 7.0.2, 7.1 | Patch available | CNA |
- Linux VendorLinux Affected 5.15 and later Fixed in 6.1.175, 6.6.136, 6.12.84, 6.18.25, 7.0.2, 7.1 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.15 to before 6.6.136; 6.7 to before 6.12.84; 6.13 to before 6.18.25; 6.19 to before 7.0.2 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.15 to before 6.6.136; 6.7 to before 6.12.84; 6.13 to before 6.18.25; 6.19 to before 7.0.2 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.175, 6.6.136, 6.12.84, 6.18.25, 7.0.2, 7.1
Vendor assessments
Red Hat
Not affected: 5 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-31704
- 2026-10-03 Alias added: GHSA-xmgr-rx43-m3gf
References
Patch 5
- https://git.kernel.org/stable/c/8d5729350b236896f51379588d9a690b7fafb8db
- https://git.kernel.org/stable/c/e1955a94b6f17f4b058afa955a6f187eb3ed7615
- https://git.kernel.org/stable/c/5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43
- https://git.kernel.org/stable/c/ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7
- https://git.kernel.org/stable/c/299f962c0b02d048fb45d248b4da493d03f3175d
More Linux Kernel vulnerabilities
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- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2026-31704 · CVE Program
- CVE-2026-31704 · NVD
- FIRST EPSS
- GHSA-xmgr-rx43-m3gf · GitHub Advisory Database · CC BY 4.0
- CVE-2026-31704 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences