CVE-2026-53243 is a vulnerability in Linux Kernel
Published on June 25, 2026
rseq: Fix using an uninitialized stack variable in rseq_exit_user_update()
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.
Products Associated with CVE-2026-53243
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Affected Versions
Linux:- Version d242126fd21ab8f1631fdbc8589e43a9d4229f3b and below e12d20a63b61aaf9de4772effccf42cc9a003e58 is affected.
- Version 82f572449cfe75f12ea985986da60e11f308f77d and below 6d99479799c69c3cb588fcda19c81d8f61d64ecd is affected.
- Version 7.0.10 and below 7.0.13 is affected.