CVE-2026-31533

Description

In the Linux kernel, the following vulnerability has been resolved: net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption The -EBUSY handling in tls_do_encryption(), introduced by commit 859054147318 ("net: tls: handle backlogging of crypto requests"), has a use-after-free due to double cleanup of encrypt_pending and the scatterlist entry. When crypto_aead_encrypt() returns -EBUSY, the request is enqueued to the cryptd backlog and the async callback tls_encrypt_done() will be invoked upon completion. That callback unconditionally restores the scatterlist entry (sge->offset, sge->length) and decrements ctx->encrypt_pending. However, if tls_encrypt_async_wait() returns an error, the synchronous error path in tls_do_encryption() performs the same cleanup again, double-decrementing encrypt_pending and double-restoring the scatterlist. The double-decrement corrupts the encrypt_pending sentinel (initialized to 1), making tls_encrypt_async_wait() permanently skip the wait for pending async callbacks. A subsequent sendmsg can then free the tls_rec via bpf_exec_tx_verdict() while a cryptd callback is still pending, resulting in a use-after-free when the callback fires on the freed record. Fix this by skipping the synchronous cleanup when the -EBUSY async wait returns an error, since the callback has already handled encrypt_pending and sge restoration.

Gravité et risque d'exploitation

CVE-2026-31533 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 0.73 %, ce qui la place devant 53.3 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions 6.6.18, <=6.1.*, <=6.12.*, 6.18.23, 3ade391adc584f17b5570fd205de3ad029090368, 8590541473188741055d27b955db0777569438e3, <414fc5e5a5aff776c150f1b86770e0a25a35df3a, <2694d408b0e595024e0fc1d64ff9db0358580f74, 5.15.160, 0, 7.0, <5.15.203, <aa9facde6c5005205874c37db3fd25799d741baf, cd1bbca03f3c1d845ce274c0d0a66de8e5929f72, 6.8, <6.8, <=6.6.*, <=6.19.*, <6.1.169, 6.1.169, <0e43e0a3c94044acc74b8e0927c27972eb5a59e8, <a9b8b18364fffce4c451e6f6fd218fa4ab646705, 5.15.203, ab6397f072e5097f267abf5cb08a8004e6b17694, <=6.18.*, 6.6.135, 6.7.6, <6.6.135, 6.19.13, <=*, 13eca403876bbea3716e82cdfe6f1e6febb38754, <=5.15.*, 6.12.82, <02f3ecadb23558bbe068e6504118f1b712d4ece0, 6.1.84, <5d70eb25b41e9b010828cd12818b06a0c3b04412) 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.

Références

• https://git.kernel.org/stable/c/414fc5e5a5aff776c150f1b86770e0a25a35df3a
• https://git.kernel.org/stable/c/02f3ecadb23558bbe068e6504118f1b712d4ece0
• https://git.kernel.org/stable/c/0e43e0a3c94044acc74b8e0927c27972eb5a59e8
• https://git.kernel.org/stable/c/aa9facde6c5005205874c37db3fd25799d741baf
• https://git.kernel.org/stable/c/5d70eb25b41e9b010828cd12818b06a0c3b04412
• https://git.kernel.org/stable/c/2694d408b0e595024e0fc1d64ff9db0358580f74
• https://git.kernel.org/stable/c/a9b8b18364fffce4c451e6f6fd218fa4ab646705