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CVE-2025-40214

Vulnérabilité élevée dans Linux (Linux)

CVSS 7.8 · Élevée
EPSS 0.1%
Linux•Linux•Versions : <=6.1.*, <=6.12.*, 6.10, 6.1.141, 0, <6.10, ad081928a8b0f57f269df999a28087fce6f2b6ce, 6.18, 6.6.93, d23802221f6755e104606864067c71af8cdb6788, <=6.6.*, <db81ad20fd8aef7cc7d536c52ee5ea4c1f979128, <60e6489f8e3b086bd1130ad4450a2c112e863791, adfb68b39b39767d6bfb53e48c4f19c183765686, 6.6.117, 6.1.159, 6.12.59, <4cd8d755c7d4f515dd9abf483316aca2f1b7b0f3, <6.6.117, <=*, <=6.17.*, <20003fbb9174121b27bd1da6ebe61542ac4c327d, <1aa7e40ee850c9053e769957ce6541173891204d, <6.1.159, 6.17.9

Description

In the Linux kernel, the following vulnerability has been resolved: af_unix: Initialise scc_index in unix_add_edge(). Quang Le reported that the AF_UNIX GC could garbage-collect a receive queue of an alive in-flight socket, with a nice repro. The repro consists of three stages. 1) 1-a. Create a single cyclic reference with many sockets 1-b. close() all sockets 1-c. Trigger GC 2) 2-a. Pass sk-A to an embryo sk-B 2-b. Pass sk-X to sk-X 2-c. Trigger GC 3) 3-a. accept() the embryo sk-B 3-b. Pass sk-B to sk-C 3-c. close() the in-flight sk-A 3-d. Trigger GC As of 2-c, sk-A and sk-X are linked to unix_unvisited_vertices, and unix_walk_scc() groups them into two different SCCs: unix_sk(sk-A)->vertex->scc_index = 2 (UNIX_VERTEX_INDEX_START) unix_sk(sk-X)->vertex->scc_index = 3 Once GC completes, unix_graph_grouped is set to true. Also, unix_graph_maybe_cyclic is set to true due to sk-X's cyclic self-reference, which makes close() trigger GC. At 3-b, unix_add_edge() allocates unix_sk(sk-B)->vertex and links it to unix_unvisited_vertices. unix_update_graph() is called at 3-a. and 3-b., but neither unix_graph_grouped nor unix_graph_maybe_cyclic is changed because both sk-B's listener and sk-C are not in-flight. 3-c decrements sk-A's file refcnt to 1. Since unix_graph_grouped is true at 3-d, unix_walk_scc_fast() is finally called and iterates 3 sockets sk-A, sk-B, and sk-X: sk-A -> sk-B (-> sk-C) sk-X -> sk-X This is totally fine. All of them are not yet close()d and should be grouped into different SCCs. However, unix_vertex_dead() misjudges that sk-A and sk-B are in the same SCC and sk-A is dead. unix_sk(sk-A)->scc_index == unix_sk(sk-B)->scc_index <-- Wrong! && sk-A's file refcnt == unix_sk(sk-A)->vertex->out_degree ^-- 1 in-flight count for sk-B -> sk-A is dead !? The problem is that unix_add_edge() does not initialise scc_index. Stage 1) is used for heap spraying, making a newly allocated vertex have vertex->scc_index == 2 (UNIX_VERTEX_INDEX_START) set by unix_walk_scc() at 1-c. Let's track the max SCC index from the previous unix_walk_scc() call and assign the max + 1 to a new vertex's scc_index. This way, we can continue to avoid Tarjan's algorithm while preventing misjudgments.

Gravité et risque d'exploitation

CVE-2025-40214 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.15 %, ce qui la place devant 3.6 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 6.10, 6.1.141, 0, <6.10, ad081928a8b0f57f269df999a28087fce6f2b6ce, 6.18, 6.6.93, d23802221f6755e104606864067c71af8cdb6788, <=6.6.*, <db81ad20fd8aef7cc7d536c52ee5ea4c1f979128, <60e6489f8e3b086bd1130ad4450a2c112e863791, adfb68b39b39767d6bfb53e48c4f19c183765686, 6.6.117, 6.1.159, 6.12.59, <4cd8d755c7d4f515dd9abf483316aca2f1b7b0f3, <6.6.117, <=*, <=6.17.*, <20003fbb9174121b27bd1da6ebe61542ac4c327d, <1aa7e40ee850c9053e769957ce6541173891204d, <6.1.159, 6.17.9) 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

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