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ReviewHigh

CVE-2026-80550

Linux

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) returni...

CVSS
7.9
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.08.27
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.9

Vulnerability overview

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) returni...

Affected product and versions

Product
Linux
Affected versions
>= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < 0282fb1c4b638eecfe2cc558092c460911d8f7e2, >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < 907adc667d902fafbdb2d740d57b55bd025dc4cd, >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < f20be33d093ce7630c17ff7ed93caf7eaf8ac1a3, >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < af3f80ca4c8b17f20f9e588def076288fdb49e65, >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < 499a8a66b1598bfab97182aed15e0f1646074a3d, >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < 4c2e1d359d7a2b82cdf3254e4e480af9417f99fb, >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < d5d096cd9369e986d4e5153baa86b8b35c283e09, >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < a005b7f1a491ffda61bff0fd0f6548f8986fb977, >= 4.12
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L
CWE
Not available