{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64559", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.796Z", "datePublished": "2026-07-29T16:31:22.195Z", "dateUpdated": "2026-08-17T04:57:37.809Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:57:37.809Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/pkey: Check length in PKEY_VERIFYPROTK ioctl\n\nExplicitly check the buffer length request structure provided by\nuser-space and fail, if it exceeds the buffer size." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerability is reached only through the PKEY_VERIFYPROTK ioctl on the /dev/pkey character device, which requires local access to the system. There is no network-facing path to this code.\nAC:L - Triggering is fully deterministic — a single ioctl with protkey.len set to 0x20000010 wraps the u32 multiplication to a legal 128-bit keytype and drives the unchecked memcpy; no race, timing, or uncontrollable memory-layout condition is involved.\nPR:L - The pkey miscdevice is registered with .mode = 0666 and neither the open handler nor pkey_unlocked_ioctl performs any capability check, so any unprivileged local user (including a normal shell user on a shared IBM Z LPAR or z/VM guest) can issue the ioctl.\nUI:N - The attacker performs the entire attack via its own ioctl call; no action by any other user or administrator is needed.\nS:U - The out-of-bounds read and write are confined to kernel memory within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The unchecked memcpy performs a huge out-of-bounds read that walks off the 64-byte on-stack protkey buffer through the entire kernel stack, relocating arbitrary kernel stack contents — including protected key material handled by this crypto driver — into heap objects, an unbounded kernel memory disclosure primitive.\nI:H - This is a massive slab out-of-bounds write into an 80-byte kmalloc-96 allocation whose first 64 bytes are entirely attacker-supplied and whose subsequent bytes come from groomable kernel-stack data, corrupting adjacent slab objects and providing a heap-overflow primitive suitable for control-flow hijacking.\nA:H - The smallest length that bypasses the keytype check requests a 512 MB copy, so the source pointer inevitably hits the VMAP_STACK guard page, producing an unhandled kernel fault/oops and panic after wide-scale heap corruption — a guaranteed, repeatable denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/s390/crypto/pkey_api.c" ], "versions": [ { "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435", "lessThan": "0a9e34ccbe772b8f321388cdbdf4f22b94e513e7", "status": "affected", "versionType": "git" }, { "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435", "lessThan": "693bf91d4db134f9b1c2840c8e287eee3d993bac", "status": "affected", "versionType": "git" }, { "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435", "lessThan": "7e7e03848c918aa0acad5ffd75d929e3afec1554", "status": "affected", "versionType": "git" }, { "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435", "lessThan": "b3d4ab2d7df9426f7f1d3671d7e2108f2ca6e970", "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/crypto/pkey_api.c" ], "versions": [ { "version": "6.12", "status": "affected" }, { "version": "0", "lessThan": "6.12", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "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": "6.12", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0a9e34ccbe772b8f321388cdbdf4f22b94e513e7" }, { "url": "https://git.kernel.org/stable/c/693bf91d4db134f9b1c2840c8e287eee3d993bac" }, { "url": "https://git.kernel.org/stable/c/7e7e03848c918aa0acad5ffd75d929e3afec1554" }, { "url": "https://git.kernel.org/stable/c/b3d4ab2d7df9426f7f1d3671d7e2108f2ca6e970" } ], "title": "s390/pkey: Check length in PKEY_VERIFYPROTK ioctl", "x_generator": { "engine": "bippy-1.2.0" } } } }