CVE Catalog

CVE-2026-53243

MediumCVSS 5.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.11%

2th percentile - higher than 2% of all known CVEs

Summary

A vulnerability in the Linux kernel uses an uninitialized stack variable in rseq_exit_user_update(). The issue stems from undefined initialization order in C structure fields, causing kernel information leak.

Risk Assessment

The vulnerability may leak sensitive kernel memory data to user space, allowing an attacker to obtain system state information.

Recommendation

Immediately update the Linux kernel to a version containing the fix that moves the ids.node_id assignment outside the structure initialization.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: rseq: Fix using an uninitialized stack variable in rseq_exit_user_update() There is an bug in which an uninitialized stack variable is used in rseq_exit_user_update() as reported by syzbot: BUG: KMSAN: kernel-infoleak in rseq_set_ids_get_csaddr include/linux/rseq_entry.h:502 [inline] The local variable: struct rseq_ids ids = { .cpu_id = task_cpu(t), .mm_cid = task_mm_cid(t), .node_id = cpu_to_node(ids.cpu_id), }; According to the C standard, the evaluation order of expressions in an initializer list is indeterminately sequenced. The compiler (Clang, in this KMSAN build) evaluates `cpu_to_node(ids.cpu_id)` *before* `ids.cpu_id` is initialized with `task_cpu(t)`. This is fixed by moving the assignment of ids.node_id outside the structure initialization.

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