{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-80550", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.766Z", "datePublished": "2026-08-26T14:37:19.956Z", "dateUpdated": "2026-10-16T19:26:26.153Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-27T05:01:38.029Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio_ccw: Fix out of bounds check on CCW array\n\nThe routine ccwchain_calc_length() counts the number of channel\ncommand words (CCWs) that are chained together in a single channel\nprogram, and rejects anything larger than CCWCHAIN_LEN_MAX (256) CCWs.\n\nThe loop itself is \"do..while (count < 257)\", and while the logic in\nis_cpa_within_range() correctly adjusts between the 0-index array of\nCCWs and the count of CCWs starting at 1, this means it would look\nat a possible 257th CCW before ending the loop and (correctly)\nreturning an error.\n\nFix this by restructuring the loop to break as soon as 256 CCWs\n(thus indexes 0-255) are examined, without looking at memory\noutside the range." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L", "baseScore": 7.9, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached only via local VFIO-ccw mediated-device write() on the I/O region (guest channel program relayed by QEMU into fsm_io_request→cp_init→ccwchain_calc_length); vfio-ccw has no network, adjacent-radio, or physical-bus entry point.\nAC:L - An attacker fully controls guest channel program content and can reliably submit 256 command-chained CCWs so ccwchain_calc_length() reaches the 257th iteration; no race, special timing, or uncontrollable heap layout is required beyond crafting the CCW chain.\nPR:N - A malicious KVM guest with an assigned vfio-ccw mediated subchannel needs no host credentials or capabilities; it triggers the bug by issuing normal guest I/O that QEMU forwards through VFIO, without init-namespace root or admin setup privileges at exploit time.\nUI:N - Exploitation requires only the attacker's own channel program submission through VFIO passthrough I/O once the device is assigned; no separate victim mount, click, or other user action is needed.\nS:C - Guest-supplied channel programs are parsed in the host kernel cp_init() path during vfio-ccw device passthrough on IBM Z/LinuxONE, so the out-of-bounds read crosses the guest-to-host VFIO virtualization boundary and can compromise hypervisor memory outside the VM security scope.\nC:H - ccwchain_calc_length() reads one struct ccw1 (8 bytes) past the 256-element guest_cp kmalloc buffer when all CCWs are chained, constituting a kernel heap out-of-bounds read of adjacent slab memory that per kernel guidance enables information disclosure primitives.\nI:N - The vulnerability is a single out-of-bounds read used only for chain/TIC validation before returning -EINVAL; it performs no out-of-bounds write and does not modify host or guest data, channel program state, or kernel control structures on the error path.\nA:L - The out-of-bounds read typically does not crash production kernels because the access stays within the same kmalloc slab page, but KASAN-instrumented or hardened builds can detect it and fault; availability impact is limited rather than a reliable host panic." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/s390/cio/vfio_ccw_cp.c" ], "versions": [ { "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "lessThan": "0282fb1c4b638eecfe2cc558092c460911d8f7e2", "status": "affected", "versionType": "git" }, { "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "lessThan": "907adc667d902fafbdb2d740d57b55bd025dc4cd", "status": "affected", "versionType": "git" }, { "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "lessThan": "f20be33d093ce7630c17ff7ed93caf7eaf8ac1a3", "status": "affected", "versionType": "git" }, { "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "lessThan": "af3f80ca4c8b17f20f9e588def076288fdb49e65", "status": "affected", "versionType": "git" }, { "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "lessThan": "499a8a66b1598bfab97182aed15e0f1646074a3d", "status": "affected", "versionType": "git" }, { "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "lessThan": "4c2e1d359d7a2b82cdf3254e4e480af9417f99fb", "status": "affected", "versionType": "git" }, { "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "lessThan": "d5d096cd9369e986d4e5153baa86b8b35c283e09", "status": "affected", "versionType": "git" }, { "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "lessThan": "a005b7f1a491ffda61bff0fd0f6548f8986fb977", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/s390/cio/vfio_ccw_cp.c" ], "versions": [ { "version": "4.12", "status": "affected" }, { "version": "0", "lessThan": "4.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.266", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.217", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.184", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.153", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.105", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.46", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.10", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "5.10.266" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "5.15.217" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "6.1.184" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "6.6.153" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "6.12.105" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "6.18.46" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "7.1.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0282fb1c4b638eecfe2cc558092c460911d8f7e2" }, { "url": "https://git.kernel.org/stable/c/907adc667d902fafbdb2d740d57b55bd025dc4cd" }, { "url": "https://git.kernel.org/stable/c/f20be33d093ce7630c17ff7ed93caf7eaf8ac1a3" }, { "url": "https://git.kernel.org/stable/c/af3f80ca4c8b17f20f9e588def076288fdb49e65" }, { "url": "https://git.kernel.org/stable/c/499a8a66b1598bfab97182aed15e0f1646074a3d" }, { "url": "https://git.kernel.org/stable/c/4c2e1d359d7a2b82cdf3254e4e480af9417f99fb" }, { "url": "https://git.kernel.org/stable/c/d5d096cd9369e986d4e5153baa86b8b35c283e09" }, { "url": "https://git.kernel.org/stable/c/a005b7f1a491ffda61bff0fd0f6548f8986fb977" } ], "title": "s390/vfio_ccw: Fix out of bounds check on CCW array", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-80550", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:17:08.790140Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:26.153Z" } } ] } }