CVE-2026-98900 xen/gntalloc: validate grant count before allocation

Not scored Published 23 Oct 2026 Updated 26 Oct 2026

Exploited in the wild: Not known
Fix: Available

What is CVE-2026-98900?

CVE-2026-98900 is a vulnerability in Linux, published on 23 Oct 2026.

Official description

In the Linux kernel, the following vulnerability has been resolved:

xen/gntalloc: validate grant count before allocation

gntalloc_ioctl_alloc() allocates the grant-id array before checking whether the requested count fits within the global grant limit. Counts above that limit cannot succeed, so reject them before the user-controlled allocation reaches kcalloc().

Use a subtraction-based check while holding gref_mutex so adding the requested count cannot wrap. Also cast the count before advancing the per-file index so the page-size multiplication is performed in 64-bit arithmetic.

Which versions are affected by CVE-2026-98900?

How do I fix CVE-2026-98900?

Upgrade to a fixed version.

Is CVE-2026-98900 being exploited?

There is no known exploitation of CVE-2026-98900 in the wild and no public exploit code.

Sources

Also known as AZL-110656, BELL-CVE-2026-98900, DEBIAN-CVE-2026-98900, GHSA-mwrq-hx54-3h97, UBUNTU-CVE-2026-98900.