High 7.8Published Aug 15, 2026

CVE-2026-74496fou: Fix use-after-free in fou_create()

Updated under an hour ago (Oct 27, 2026, 12:40 PM ET)

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In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release().

CVSS: 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Received
Record last updated: Oct 16, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	23461551c00628c3f3fe9cf837bf53cf8f212b63 builds before 0ee628a58d83e571f36ec9f07624d6845e420c50; from 23461551c00628c3f3fe9cf837bf53cf8f212b63 before a6fca682cfa2041e31aa72cc397c4a1406eb7468; from 23461551c00628c3f3fe9cf837bf53cf8f212b63 before b3f9c3e60aa25453774f899d25b5e61dd0bec1d5; 23461551c00628c3f3fe9cf837bf53cf8f212b63 builds before 99f4d3120b244f92e5df787152041296a2860cb5; from 23461551c00628c3f3fe9cf837bf53cf8f212b63 before 58835985c035a8333742f829ad7e0889a082f9d3; 23461551c00628c3f3fe9cf837bf53cf8f212b63 builds before 9042867d4701728f0c6527215b11471759904d8f; from 23461551c00628c3f3fe9cf837bf53cf8f212b63 before a28d8903bfe76089ea4bbdbff9976965f9ef8107; from 23461551c00628c3f3fe9cf837bf53cf8f212b63 before b14361aca6350ff7907b0e9903c7b94dc7d5d4a0	CNA record

References

References

https://git.kernel.org/stable/c/0ee628a58d83e571f36ec9f07624d6845e420c50
https://git.kernel.org/stable/c/a6fca682cfa2041e31aa72cc397c4a1406eb7468
https://git.kernel.org/stable/c/b3f9c3e60aa25453774f899d25b5e61dd0bec1d5
https://git.kernel.org/stable/c/99f4d3120b244f92e5df787152041296a2860cb5
https://git.kernel.org/stable/c/58835985c035a8333742f829ad7e0889a082f9d3
https://git.kernel.org/stable/c/9042867d4701728f0c6527215b11471759904d8f
https://git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107
https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.