{"id":"CVE-2026-74496","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74496","summary":"fou: Fix use-after-free in fou_create()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nfou: Fix use-after-free in fou_create()\n\nfou_create() publishes struct fou through sk_user_data before adding the\nnew FOU port to the per-netns list.  If fou_add_to_port_list() fails,\nthe error path frees fou while it is still reachable through\nsk_user_data.  A concurrent receive can then dereference the freed\nobject in fou_from_sock().\n\nThis ordering issue was previously noted in the linked discussion.\n\nThe failure is reachable when local port 0 is requested.  Each socket\nbinds to a different ephemeral port, but fou_cfg_cmp() compares the\nrequested port 0 and reports -EALREADY once an entry already exists.\n\nRelease the tunnel socket before freeing fou so sk_user_data is cleared\nfirst, and defer reclamation with kfree_rcu() to protect concurrent RCU\nreaders.  This matches the lifetime handling in fou_release().","published":"2026-08-15T12:27:23.854Z","modified":"2026-08-17T03:47:34.754526934Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"7.1.8"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74496.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74496"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-17T03:47:34.754526934Z"}}