CVE-2026-45890
In the Linux kernel, the following vulnerability has been resolved: xen-netback: reject zero-queue configuration from guest A malicious or buggy Xen guest can write "0" to the xenbus key "multi-queue-num-queues". The connect() function in the backend only validates the upper bound (requested_num_queues > xenvif_max_queues) but not zero, allowing requested_num_queues=0 to reach vzalloc(array_size(0, sizeof(struct xenvif_queue))), which triggers WARN_ON_ONCE(!size) in __vmalloc_node_range(). On systems with panic_on_warn=1, this allows a guest-to-host denial of service. The Xen network interface specification requires the queue count to be "greater than zero". Add a zero check to match the validation already present in xen-blkback, which has included this guard since its multi-queue support was added.
Affected versions
Linux kernel versions
3.16
and later are affected. Fixed in
5.10.252,
5.15.202,
6.1.165,
6.6.128,
6.12.75,
6.18.14,
6.19.4,
7.0
and their respective stable series.
References
The following references provide additional information about CVE-2026-45890 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.
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PatchKernel patch commithttps://git.kernel.org/stable/c/2993e0f904c45f8af12917344bb1cac7ccd05a60
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PatchKernel patch commithttps://git.kernel.org/stable/c/654780dee9eae419e1648ea58462c4efe54518fa
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PatchKernel patch commithttps://git.kernel.org/stable/c/6d1dc8014334c7fb25719999bca84d811e60a559
Frequently asked questions
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What is CVE-2026-45890?
CVE-2026-45890 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 3.16 onward and has been patched in 5.10.252, 5.15.202, 6.1.165 and others. CVE-2026-45890 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-45890?
Yes — CVE-2026-45890 has been patched. Fixed versions include 5.10.252, 5.15.202, 6.1.165 and others. If you are running Linux kernel 3.16 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-45890 actively exploited?
No — CVE-2026-45890 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.