What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-26 · updated 2026-10-16

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.

Affected products

• Linux kernel: 4.12 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 7.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/06f4d6e5a8af6c2072e8cd39dbc512c683ca7fb2
• https://git.kernel.org/stable/c/15fb4559a7fdf0b8725e433a71cfd03a1313a48b
• https://git.kernel.org/stable/c/4ee94790490ae8dcc97df8597f07836c8a81bbcf
• https://git.kernel.org/stable/c/5405c90d6a47b3014e74ee0618a162449abbbc93
• https://git.kernel.org/stable/c/a1625f66eaa1200068a0e2c05bc90e65182fc4e3

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