In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race `packet_release()` has a race window where `NETDEV_UP` can re-register a socket into a fanout group's `arr[]` array. The re-registration is not cleaned up by `fanout_release()`, leaving a dangling pointer in the fanout array. `packet_release()` does NOT zero `po->num` in its `bind_lock` section. After releasing `bind_lock`, `po->num` is still non-zero and `po->ifindex` still matches the bound device. A concurrent `packet_notifier(NETDEV_UP)` that already found the socket in `sklist` can re-register the hook. For fanout sockets, this re-registration calls `__fanout_link(sk, po)` which adds the socket back into `f->arr[]` and increments `f->num_members`, but does NOT increment `f->sk_ref`. The fix sets `po->num` to zero in `packet_release` while `bind_lock` is held to prevent NETDEV_UP from linking, preventing the race window. This bug was found following an additional audit with Claude Code based on CVE-2025-38617.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | HIGH |
| Integrity Impact | HIGH |
| Availability Impact | HIGH |
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Type: Secondary
Exploitability Score: 1.8
Impact Score: 5.9
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-416
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde03c4c0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde03d200> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdc51a000> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdc373d00> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde03ed40> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde03cd40> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde03c2c0> | Operating System |
| linux | linux_kernel | 3.1 | <built-in method update of dict object at 0x702bde03fd40> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bde03f100> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bde03f300> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc5190c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc372680> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc371640> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc3737c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bde03e140> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:3.1:-:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* |