In the Linux kernel, the following vulnerability has been resolved:
net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd()
In tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points
directly into the mmap'd TX ring buffer shared with userspace. The
kernel validates the header via __packet_snd_vnet_parse() but then
re-reads all fields later in virtio_net_hdr_to_skb(). A concurrent
userspace thread can modify the vnet_hdr fields between validation
and use, bypassing all safety checks.
The non-TPACKET path (packet_snd()) already correctly copies vnet_hdr
to a stack-local variable. All other vnet_hdr consumers in the kernel
(tun.c, tap.c, virtio_net.c) also use stack copies. The TPACKET TX
path is the only caller of virtio_net_hdr_to_skb() that reads directly
from user-controlled shared memory.
Fix this by copying vnet_hdr from the mmap'd ring buffer to a
stack-local variable before validation and use, consistent with the
approach used in packet_snd() and all other callers.
References
Configurations
Configuration 1 (hide)
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History
06 May 2026, 19:01
| Type | Values Removed | Values Added |
|---|---|---|
| CWE | CWE-362 | |
| First Time |
Linux
Linux linux Kernel |
|
| CPE | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* |
|
| References | () https://git.kernel.org/stable/c/28324a3b62d9ce7f9bdd65a8ce63f382041d1b27 - Patch | |
| References | () https://git.kernel.org/stable/c/2c054e17d9d41f1020376806c7f750834ced4dc5 - Patch | |
| References | () https://git.kernel.org/stable/c/3a1bf9116ea31470b89692585c3910dfe830dcdd - Patch | |
| References | () https://git.kernel.org/stable/c/48a6ef291a17639e1b6ae0fbe9c8b2bb87d7804b - Patch | |
| References | () https://git.kernel.org/stable/c/74e2db36fe50e3ad9d5300d7fd0e6e2a15a6d121 - Patch |
03 May 2026, 07:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.8 |
01 May 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-05-01 14:16
Updated : 2026-05-06 19:01
NVD link : CVE-2026-31700
Mitre link : CVE-2026-31700
CVE.ORG link : CVE-2026-31700
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-362
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')