{"id":"CVE-2026-64558","state":"PUBLISHED","title":"s390/pkey: Check length in pkey_pckmo handler implementation","description":"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.","publishedAt":"2026-07-29T16:31:21.591Z","updatedAt":"2026-10-19T20:48:41.175Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8fcc231ce3bea12b78bb94b280cdc03cff342435","status":"affected","lessThan":"02028a24e26d85262ab9c8fc4344e1f3503007fc","versionType":"git"},{"version":"8fcc231ce3bea12b78bb94b280cdc03cff342435","status":"affected","lessThan":"433e5e70cdc1edf382d28d08a885b22e2b98b7da","versionType":"git"},{"version":"8fcc231ce3bea12b78bb94b280cdc03cff342435","status":"affected","lessThan":"614aa0491c7a190556c2345dddee0b6f5ed90989","versionType":"git"},{"version":"8fcc231ce3bea12b78bb94b280cdc03cff342435","status":"affected","lessThan":"1ac287e2af9a9112fe271427ef45eceb26bce8b4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/crypto/pkey_pckmo.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/crypto/pkey_pckmo.c"]}],"references":["https://git.kernel.org/stable/c/02028a24e26d85262ab9c8fc4344e1f3503007fc","https://git.kernel.org/stable/c/433e5e70cdc1edf382d28d08a885b22e2b98b7da","https://git.kernel.org/stable/c/614aa0491c7a190556c2345dddee0b6f5ed90989","https://git.kernel.org/stable/c/1ac287e2af9a9112fe271427ef45eceb26bce8b4"],"weaknesses":["CWE-122"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64558.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64558","state":"PUBLISHED","datePublished":"2026-07-29T16:31:21.591Z","dateUpdated":"2026-10-19T20:48:41.175Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.796Z"},"containers":{"cna":{"title":"s390/pkey: Check length in pkey_pckmo handler implementation","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8fcc231ce3bea12b78bb94b280cdc03cff342435","status":"affected","lessThan":"02028a24e26d85262ab9c8fc4344e1f3503007fc","versionType":"git"},{"version":"8fcc231ce3bea12b78bb94b280cdc03cff342435","status":"affected","lessThan":"433e5e70cdc1edf382d28d08a885b22e2b98b7da","versionType":"git"},{"version":"8fcc231ce3bea12b78bb94b280cdc03cff342435","status":"affected","lessThan":"614aa0491c7a190556c2345dddee0b6f5ed90989","versionType":"git"},{"version":"8fcc231ce3bea12b78bb94b280cdc03cff342435","status":"affected","lessThan":"1ac287e2af9a9112fe271427ef45eceb26bce8b4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/crypto/pkey_pckmo.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/crypto/pkey_pckmo.c"]}],"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:57:36.699Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64558","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:42:40.566840Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-122","lang":"en","type":"CWE","description":"CWE-122 Heap-based Buffer Overflow"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:48:41.175Z"}}]}}}