CVE-2026-64523
Vulnérabilité critique dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: net/handshake: Take a long-lived file reference at submit handshake_nl_accept_doit() needs the file pointer backing req->hr_sk->sk_socket to survive the window between handshake_req_next() and the subsequent FD_PREPARE() and get_file(). The submit-side sock_hold() does not provide that. sk_refcnt keeps struct sock alive, but struct socket is owned by sock->file: when the consumer fputs the last file reference, sock_release() tears the socket down regardless of any sock_hold. Add an hr_file pointer to struct handshake_req and acquire an explicit reference on sock->file during handshake_req_submit(). handshake_complete() and handshake_req_cancel() release the reference on the completion-bit-winning path. The submit error path must also release the file reference, but after rhashtable insertion a concurrent handshake_req_cancel() can discover the request and race the error path. Gate the error-path cleanup -- sk_destruct restoration, fput, and request destruction -- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same serialization handshake_complete() and handshake_req_cancel() already use. When cancel has already claimed ownership, the submit error path returns without touching the request; socket teardown handles final destruction. The accept-side dereferences are not yet retargeted; that change comes in the next patch.
Gravité et risque d'exploitation
CVE-2026-64523 obtient un score CVSS de 9.8/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.67 %, ce qui la place devant 51.1 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 6.4, <=7.0.*, 7.0.12, <=6.12.*, 3b3009ea8abb713b022d94fba95ec270cf6e7eae, <=*, <b913801ad9b9a51437d84d030ec6843e08976bd6, 6.12.93, <=6.18.*, 7.1, <685b10dd0e32c7782cead16c8cf055c609678583, 6.18.44, <16eaba5aa89c04eea125905bb8f988c1897f4f29, 0, <09dba37eee70d0596e26645015f1aa95a9848e9d, <6.4) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.