{"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": "2026-08-27T05:01:38.029Z"}, "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\u2192cp_init\u2192ccwchain_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"}, 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"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": 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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/s390/cio/vfio_ccw_cp.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "0282fb1c4b638eecfe2cc558092c460911d8f7e2", "status": "affected", "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "versionType": "git"}, {"lessThan": "907adc667d902fafbdb2d740d57b55bd025dc4cd", "status": "affected", "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "versionType": "git"}, {"lessThan": "f20be33d093ce7630c17ff7ed93caf7eaf8ac1a3", "status": "affected", "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "versionType": "git"}, {"lessThan": "af3f80ca4c8b17f20f9e588def076288fdb49e65", "status": "affected", "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "versionType": "git"}, {"lessThan": "499a8a66b1598bfab97182aed15e0f1646074a3d", "status": "affected", "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "versionType": "git"}, {"lessThan": "4c2e1d359d7a2b82cdf3254e4e480af9417f99fb", "status": "affected", "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "versionType": "git"}, {"lessThan": "d5d096cd9369e986d4e5153baa86b8b35c283e09", "status": "affected", "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "versionType": "git"}, {"lessThan": "a005b7f1a491ffda61bff0fd0f6548f8986fb977", "status": "affected", "version": "0a19e61e6d4c6192077ead760ba0a2d350987d4c", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/s390/cio/vfio_ccw_cp.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.12"}, {"lessThan": "4.12", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.266", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.217", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.184", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.153", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.105", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.46", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.10", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "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."}], "id": "CVE-2026-80550", "lastModified": "2026-08-27T06:17:37.617", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "LOW", "baseScore": 7.9, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L", "version": "3.1"}, "exploitabilityScore": 2.5, "impactScore": 4.7, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-26T15:17:09.477", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0282fb1c4b638eecfe2cc558092c460911d8f7e2"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/499a8a66b1598bfab97182aed15e0f1646074a3d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4c2e1d359d7a2b82cdf3254e4e480af9417f99fb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/907adc667d902fafbdb2d740d57b55bd025dc4cd"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a005b7f1a491ffda61bff0fd0f6548f8986fb977"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/af3f80ca4c8b17f20f9e588def076288fdb49e65"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d5d096cd9369e986d4e5153baa86b8b35c283e09"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f20be33d093ce7630c17ff7ed93caf7eaf8ac1a3"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: s390/vfio_ccw: Fix out of bounds check on CCW array", "id": "2524463", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2524463"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-125", "details": ["In the Linux kernel, the following vulnerability has been resolved:\ns390/vfio_ccw: Fix out of bounds check on CCW array\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.\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.\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.", "A flaw was found in the `s390/vfio_ccw` component of the Linux kernel. The `ccwchain_calc_length()` routine, which counts channel command words (CCWs), incorrectly checked array boundaries. This could lead to an out-of-bounds read, where the system attempts to access memory beyond its allocated limits. Such an issue could potentially cause system instability or lead to the disclosure of sensitive information."], "name": "CVE-2026-80550", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-26T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-80550\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-80550\nhttps://lore.kernel.org/linux-cve-announce/2026082608-CVE-2026-80550-5cb8@gregkh/T"], "threat_severity": "Moderate"}