{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64558", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.796Z", "datePublished": "2026-07-29T16:31:21.591Z", "dateUpdated": "2026-08-17T04:57:36.699Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:57:36.699Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/pkey: Check length in pkey_pckmo handler implementation\n\nExplicitly check the length of the target buffer in the pkey_pckmo\nimplementation of the key_to_protkey() handler function. The handler\nfunction fails, if the generated output data exceeds the length of the\nprovided target buffer." } ], "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 vulnerable path is entered through the PKEY_KBLOB2PROTK/PKEY_KBLOB2PROTK2 ioctls on the /dev/pkey character device, or via an AF_ALG setkey on the paes skciphers. Both require local system access; no network input reaches this code.\nAC:L - A single ioctl with a hand-crafted 176-byte protected-key token (type 0x00, version TOKVER_PROTECTED_KEY, keytype PKEY_KEYTYPE_HMAC_1024, len 160) deterministically triggers the 96-byte overflow; there is no race, no memory-layout dependency, and no hardware or wrapping-key prerequisite since the non-AES branch skips pckmo_verify_protkey().\nPR:L - /dev/pkey is registered as a miscdevice with .mode = 0666 and pkey_unlocked_ioctl() contains no capability or permission check, so any unprivileged local user can reach the bug; the paes/AF_ALG setkey path likewise requires no privileges.\nUI:N - The attacker triggers the overflow entirely on their own via a single ioctl or socket option call; no victim action, mount, or file open is involved.\nS:U - The corruption is confined to the kernel's own stack within the same security authority; exploitation yields kernel privilege escalation rather than crossing a VM, IOMMU, or sandbox boundary.\nC:H - The attacker gains a fully controlled 96-byte out-of-bounds stack write that can clobber adjacent locals, saved pointers and return addresses, which is readily leveraged into arbitrary kernel memory disclosure; the copy also leaves *protkeylen inflated to 160 while the buffer is 64 bytes, feeding an oversized length back to callers.\nI:H - This is an out-of-bounds write of 96 attacker-chosen bytes past the end of a kernel stack object (the last member of struct pkey_kblob2pkey), overwriting saved registers and the return address — a classic control-flow hijack / local privilege escalation primitive.\nA:H - Smashing the kernel stack past the canary reliably produces a stack-protector panic or an oops on return, and any unprivileged user can repeat it at will to crash the machine." } ] } ], "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_pckmo.c" ], "versions": [ { "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435", "lessThan": "02028a24e26d85262ab9c8fc4344e1f3503007fc", "status": "affected", "versionType": "git" }, { "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435", "lessThan": "433e5e70cdc1edf382d28d08a885b22e2b98b7da", "status": "affected", "versionType": "git" }, { "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435", "lessThan": "614aa0491c7a190556c2345dddee0b6f5ed90989", "status": "affected", "versionType": "git" }, { "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435", "lessThan": "1ac287e2af9a9112fe271427ef45eceb26bce8b4", "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_pckmo.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/02028a24e26d85262ab9c8fc4344e1f3503007fc" }, { "url": "https://git.kernel.org/stable/c/433e5e70cdc1edf382d28d08a885b22e2b98b7da" }, { "url": "https://git.kernel.org/stable/c/614aa0491c7a190556c2345dddee0b6f5ed90989" }, { "url": "https://git.kernel.org/stable/c/1ac287e2af9a9112fe271427ef45eceb26bce8b4" } ], "title": "s390/pkey: Check length in pkey_pckmo handler implementation", "x_generator": { "engine": "bippy-1.2.0" } } } }