# CVE-2026-80554: s390/vfio_ccw: Limit the number of channel program segments

CVE-2026-80554 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-80554, released August 27, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-80554
- Priority: High
- CVSS: 9.3 (Moderate)
- EPSS: 0.0014
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 26, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-80554

## Description

In the Linux kernel, the following vulnerability has been resolved:  s390/vfio_ccw: Limit the number of channel program segments  The processing of channel programs, and the CCWs within them, is done recursively. As such, there is an arbitrary (but not architectural) limit to the number of CCWs that can exist in a single channel program.  The vfio-ccw logic breaks these channel programs into segments whenever it encounters a Transfer-In-Channel (TIC) CCW, and the combined number of segments count towards the global limit. Impose an equivalent limit to the number of segments until such logic can be made non-recursive.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.105-1 | [DEBIAN-CVE-2026-80554](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80554.md) | Aug 27, 2026 |
| Linux | linux Debian 14 | 7.1.10-1 | [DEBIAN-CVE-2026-80554](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80554.md) | Aug 27, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.107-1~deb12u1 | [DEBIAN-CVE-2026-80554](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80554.md) | Aug 27, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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