CVE-2026-64232 block: recompute nr_integrity_segments in blk_insert_cloned_request

What is CVE-2026-64232?

CVE-2026-64232 is a critical denial of service vulnerability in Linux kernel, published on 24 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

block: recompute nr_integrity_segments in blk_insert_cloned_request

blk_insert_cloned_request() already recomputes nr_phys_segments against the bottom queue, because "the queue settings related to segment counting may differ from the original queue." The exact same reasoning applies to integrity segments: a stacked driver's underlying queue can have tighter virt_boundary_mask, seg_boundary_mask, or max_segment_size than the top queue, in which case blk_rq_count_integrity_sg() against the bottom queue produces a different count than the cached rq->nr_integrity_segments inherited from the source request by blk_rq_prep_clone().

When the cached count is lower than the bottom queue's actual count, blk_rq_map_integrity_sg() trips

BUG_ON(segments > rq->nr_integrity_segments);

on dispatch. The same families of stacked setups that motivated the existing nr_phys_segments recompute -- dm-multipath fanning out to nvme-rdma in particular -- can produce this.

Mirror the nr_phys_segments handling: when the request carries integrity, recompute nr_integrity_segments against the bottom queue and reject the request if it exceeds the bottom queue's max_integrity_segments. blk_rq_count_integrity_sg() and queue_max_integrity_segments() are both already available via <linux/blk-integrity.h>, which blk-mq.c includes.

This closes a latent gap in the stacking contract and brings the integrity-segment accounting in line with the existing phys-segment accounting.

Weakness: CWE-667

Which versions are affected by CVE-2026-64232?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64232?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-64232 being exploited?

There is no known exploitation of CVE-2026-64232 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-64232, DEBIAN-CVE-2026-64232, GHSA-g8pp-85q4-6cgq, ROOT-OS-UBUNTU-2204-CVE-2026-64232, UBUNTU-CVE-2026-64232.