{"id":"CVE-2026-80546","state":"PUBLISHED","title":"s390/zcrypt: Improve CCA CPRB length and overflow checks","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/zcrypt: Improve CCA CPRB length and overflow checks\n\nThe xcrb_msg_to_type6cprb_msgx() function lacks proper input\nvalidation, creating security vulnerabilities:\n1. Integer overflow after CEIL4 alignment: Signed int variables could\n   overflow during 4-byte boundary alignment, causing undersized\n   buffer allocations or incorrect bounds checking.\n2. Missing minimum size validation: The CPRBX structure is copied from\n   userspace without verifying sufficient buffer length. Undersized\n   buffers cause uninitialized memory access when reading structure\n   fields like cprbx.cprb_len and cprbx.domain.\n3. Arithmetic overflow in sum calculations: Adding control block and\n   data block sizes could overflow, bypassing size checks and enabling\n   buffer overflows.\n\nFix by using size_t for length calculations, adding U32_MAX boundary\nchecks after alignment, validating minimum control block size before\ncopying from userspace, and detecting sum calculation overflows.","publishedAt":"2026-08-26T14:37:17.550Z","updatedAt":"2026-10-21T12:46:29.446Z","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":"20b0b0159390fa5c00a435195649680fefda81e0","status":"affected","lessThan":"584400144020f40365de3972c4763da520e7280e","versionType":"git"},{"version":"e2c6d91eb8b1533753755f07803e47eceed263d0","status":"affected","lessThan":"50fe5133dcb46449daf2435fa705264364411129","versionType":"git"},{"version":"e2c6d91eb8b1533753755f07803e47eceed263d0","status":"affected","lessThan":"35ac6754ba6da45fd193f5ce3f665f7490b830d5","versionType":"git"},{"version":"f9da85d4780515f65983e0af151458599adaef3d","status":"affected","versionType":"git"},{"version":"6.12.114","status":"affected","lessThan":"6.13","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/crypto/zcrypt_msgtype6.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"7.1.10","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/zcrypt_msgtype6.c"]}],"references":["https://git.kernel.org/stable/c/584400144020f40365de3972c4763da520e7280e","https://git.kernel.org/stable/c/50fe5133dcb46449daf2435fa705264364411129","https://git.kernel.org/stable/c/35ac6754ba6da45fd193f5ce3f665f7490b830d5"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80546.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80546","state":"PUBLISHED","datePublished":"2026-08-26T14:37:17.550Z","dateUpdated":"2026-10-21T12:46:29.446Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.765Z"},"containers":{"cna":{"title":"s390/zcrypt: Improve CCA CPRB length and overflow checks","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/zcrypt: Improve CCA CPRB length and overflow checks\n\nThe xcrb_msg_to_type6cprb_msgx() function lacks proper input\nvalidation, creating security vulnerabilities:\n1. Integer overflow after CEIL4 alignment: Signed int variables could\n   overflow during 4-byte boundary alignment, causing undersized\n   buffer allocations or incorrect bounds checking.\n2. Missing minimum size validation: The CPRBX structure is copied from\n   userspace without verifying sufficient buffer length. Undersized\n   buffers cause uninitialized memory access when reading structure\n   fields like cprbx.cprb_len and cprbx.domain.\n3. Arithmetic overflow in sum calculations: Adding control block and\n   data block sizes could overflow, bypassing size checks and enabling\n   buffer overflows.\n\nFix by using size_t for length calculations, adding U32_MAX boundary\nchecks after alignment, validating minimum control block size before\ncopying from userspace, and detecting sum calculation overflows."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"20b0b0159390fa5c00a435195649680fefda81e0","status":"affected","lessThan":"584400144020f40365de3972c4763da520e7280e","versionType":"git"},{"version":"e2c6d91eb8b1533753755f07803e47eceed263d0","status":"affected","lessThan":"50fe5133dcb46449daf2435fa705264364411129","versionType":"git"},{"version":"e2c6d91eb8b1533753755f07803e47eceed263d0","status":"affected","lessThan":"35ac6754ba6da45fd193f5ce3f665f7490b830d5","versionType":"git"},{"version":"f9da85d4780515f65983e0af151458599adaef3d","status":"affected","versionType":"git"},{"version":"6.12.114","status":"affected","lessThan":"6.13","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/crypto/zcrypt_msgtype6.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"7.1.10","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/zcrypt_msgtype6.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/584400144020f40365de3972c4763da520e7280e"},{"url":"https://git.kernel.org/stable/c/50fe5133dcb46449daf2435fa705264364411129"},{"url":"https://git.kernel.org/stable/c/35ac6754ba6da45fd193f5ce3f665f7490b830d5"}],"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 bug is in xcrb_msg_to_type6cprb_msgx(), reached only from the ZSECSENDCPRB ioctl on the s390 zcrypt character device (zcrypt_unlocked_ioctl -> zsecsendcprb_ioctl -> _zcrypt_send_cprb -> prep_cca_ap_msg); there is no network, adjacent-radio, or physical-bus entry point.\nAC:L - An attacker with a zcrypt fd fully controls the ica_xcRB length fields and CPRB buffers and can craft values that bypass flawed CEIL4/sum checks on every ioctl; no race, timing dependency, or uncontrolled memory layout is required.\nPR:L - Exploitation needs only local access to a zcrypt device node with ZSECSENDCPRB permitted via zcrypt_check_ioctl(); on IBM Z/LinuxONE admins routinely delegate such access to non-root crypto service accounts through custom zcdn nodes, not init-namespace root alone.\nUI:N - The attacker triggers the flaw directly by issuing ZSECSENDCPRB with a crafted ica_xcRB from their own process; no separate victim action such as mounting a filesystem or opening a file is required.\nS:U - Impact is heap corruption and kernel memory disclosure within the host kernel address space during AP message preparation; it does not cross a VM, IOMMU, or other changed security-authority boundary.\nC:H - Undersized request_control_blk_length copies fewer than sizeof(CPRBX) bytes yet the code reads cprbx.cprb_len and cprbx.domain from uninitialized kmalloc memory; integer-overflow bypasses can also yield out-of-bounds reads beyond the allocated ap_msg buffer.\nI:H - Signed-int CEIL4 alignment and sum overflows can make ap_msg->len smaller than copied data and place req_data before the kmalloc buffer, enabling z_copy_from_user() heap buffer overflows and attacker-influenced memory corruption suitable for control-flow hijack.\nA:H - Heap underflow/overflow and corrupted AP message buffers can immediately oops or panic the kernel; prep_cca_ap_msg runs before any crypto hardware is required, so the crash primitive is repeatable from ioctl alone."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-21T12:46:29.446Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.1.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.114"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}