{"id":"CVE-2026-93186","state":"PUBLISHED","title":"cxl/mbox: Clamp mailbox output allocation to the payload size","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncxl/mbox: Clamp mailbox output allocation to the payload size\n\nCXL_MEM_SEND_COMMAND bounds the user's in.size to the mailbox payload\nsize but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls\nkvzalloc(out.size). A large out.size drives a huge allocation, above\nINT_MAX it WARNs and taints, and with panic_on_warn=1 it panics.\n\nThe transport __cxl_pci_mbox_send_cmd() already clamps the response copy\nto min(out.size, payload_size, device len), so the output buffer is\nnever written beyond payload_size. Clamp the allocation to payload_size\ntoo, matching the RAW path.","publishedAt":"2026-09-17T16:12:12.121Z","updatedAt":"2026-10-30T12:36:18.449Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"123f6d154253939ce38f0ec0b6d1ba67f870e01f","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"d2d40574b9b272ade32d0d77b140d990e7547f5f","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"f5d2bbf0300f46307948864fbb97bce5097f4fe2","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"31d4841eca7c4b75751ca96d24339e19303337f2","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"b4e11c731d6bee3b87315e055a1ca417c92dc1fc","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"8a13db9f899d149c3aab24abcb668121cfda5a4f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/cxl/core/mbox.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/cxl/core/mbox.c"]}],"references":["https://git.kernel.org/stable/c/123f6d154253939ce38f0ec0b6d1ba67f870e01f","https://git.kernel.org/stable/c/d2d40574b9b272ade32d0d77b140d990e7547f5f","https://git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2","https://git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2","https://git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc","https://git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f"],"weaknesses":[],"ingestedAt":"2026-10-30T12:56:04.490Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/93xxx/CVE-2026-93186.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93186","state":"PUBLISHED","datePublished":"2026-09-17T16:12:12.121Z","dateUpdated":"2026-10-30T12:36:18.449Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-17T16:02:15.091Z"},"containers":{"cna":{"title":"cxl/mbox: Clamp mailbox output allocation to the payload size","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncxl/mbox: Clamp mailbox output allocation to the payload size\n\nCXL_MEM_SEND_COMMAND bounds the user's in.size to the mailbox payload\nsize but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls\nkvzalloc(out.size). A large out.size drives a huge allocation, above\nINT_MAX it WARNs and taints, and with panic_on_warn=1 it panics.\n\nThe transport __cxl_pci_mbox_send_cmd() already clamps the response copy\nto min(out.size, payload_size, device len), so the output buffer is\nnever written beyond payload_size. Clamp the allocation to payload_size\ntoo, matching the RAW path."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"123f6d154253939ce38f0ec0b6d1ba67f870e01f","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"d2d40574b9b272ade32d0d77b140d990e7547f5f","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"f5d2bbf0300f46307948864fbb97bce5097f4fe2","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"31d4841eca7c4b75751ca96d24339e19303337f2","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"b4e11c731d6bee3b87315e055a1ca417c92dc1fc","versionType":"git"},{"version":"583fa5e71caeb79e04e477e9837e2f7fa53b71e4","status":"affected","lessThan":"8a13db9f899d149c3aab24abcb668121cfda5a4f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/cxl/core/mbox.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/cxl/core/mbox.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/123f6d154253939ce38f0ec0b6d1ba67f870e01f"},{"url":"https://git.kernel.org/stable/c/d2d40574b9b272ade32d0d77b140d990e7547f5f"},{"url":"https://git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2"},{"url":"https://git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2"},{"url":"https://git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc"},{"url":"https://git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:36:18.449Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}