CVE-2026-80550: Linux

High severity, CVSS 7.9. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Fix out of bounds check on CCW array The routine ccwchain_calc_length() counts the number of channel command words (CCWs) that are chained together in a single channel program, and rejects anything larger than CCWCHAIN_LEN_MAX (256) CCWs. The loop itself is "do..while (count < 257)", and while the logic in is_cpa_within_range() correctly adjusts between the 0-index array of CCWs and the count of CCWs starting at 1, this means it would look at a possible 257th CCW before ending the loop and (correctly) returning an error. Fix this by restructuring the loop to break as soon as 256 CCWs (thus indexes 0-255) are examined, without looking at memory outside the range.

Affected products

• Linux Linux: from 4.12, before 5.10.266 (fixed in 5.10.266); from 5.11, before 5.15.217 (fixed in 5.15.217); from 5.16, before 6.1.184 (fixed in 6.1.184); from 6.2, before 6.6.153 (fixed in 6.6.153); from 6.7, before 6.12.105 (fixed in 6.12.105); from 6.13, before 6.18.46 (fixed in 6.18.46); …

Published 2026-08-26. Last modified 2026-08-27.