CVE Catalog

CVE-2025-40214

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.13%

3th percentile - higher than 3% of all known CVEs

Summary

A vulnerability has been identified in the Linux kernel that allows for incorrect identification of socket states in the context of garbage collection. The issue arises from the lack of initialization of the SCC index in the unix_add_edge() function, leading to incorrect grouping of sockets in cyclic references.

Risk Assessment

This vulnerability may lead to improper socket management, potentially resulting in memory leaks or other performance issues. Organizations should be aware of the risks associated with the improper functioning of applications utilizing AF_UNIX.

Recommendation

It is recommended to update the Linux kernel to the latest version where this vulnerability has been resolved. Additionally, monitoring applications using AF_UNIX for potential socket management issues is advisable.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS