{"id":"CVE-2026-23327","state":"PUBLISHED","title":"cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()\n\ncxl_payload_from_user_allowed() casts and dereferences the input\npayload without first verifying its size. When a raw mailbox command\nis sent with an undersized payload (ie: 1 byte for CXL_MBOX_OP_CLEAR_LOG,\nwhich expects a 16-byte UUID), uuid_equal() reads past the allocated buffer,\ntriggering a KASAN splat:\n\nBUG: KASAN: slab-out-of-bounds in memcmp+0x176/0x1d0 lib/string.c:683\nRead of size 8 at addr ffff88810130f5c0 by task syz.1.62/2258\n\nCPU: 2 UID: 0 PID: 2258 Comm: syz.1.62 Not tainted 6.19.0-dirty #3 PREEMPT(voluntary)\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\nCall Trace:\n <TASK>\n __dump_stack lib/dump_stack.c:94 [inline]\n dump_stack_lvl+0xab/0xe0 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:378 [inline]\n print_report+0xce/0x650 mm/kasan/report.c:482\n kasan_report+0xce/0x100 mm/kasan/report.c:595\n memcmp+0x176/0x1d0 lib/string.c:683\n uuid_equal include/linux/uuid.h:73 [inline]\n cxl_payload_from_user_allowed drivers/cxl/core/mbox.c:345 [inline]\n cxl_mbox_cmd_ctor drivers/cxl/core/mbox.c:368 [inline]\n cxl_validate_cmd_from_user drivers/cxl/core/mbox.c:522 [inline]\n cxl_send_cmd+0x9c0/0xb50 drivers/cxl/core/mbox.c:643\n __cxl_memdev_ioctl drivers/cxl/core/memdev.c:698 [inline]\n cxl_memdev_ioctl+0x14f/0x190 drivers/cxl/core/memdev.c:713\n vfs_ioctl fs/ioctl.c:51 [inline]\n __do_sys_ioctl fs/ioctl.c:597 [inline]\n __se_sys_ioctl fs/ioctl.c:583 [inline]\n __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xa8/0x330 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7fdaf331ba79\nCode: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007fdaf1d77038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010\nRAX: ffffffffffffffda RBX: 00007fdaf3585fa0 RCX: 00007fdaf331ba79\nRDX: 00002000000001c0 RSI: 00000000c030ce02 RDI: 0000000000000003\nRBP: 00007fdaf33749df R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\nR13: 00007fdaf3586038 R14: 00007fdaf3585fa0 R15: 00007ffced2af768\n </TASK>\n\nAdd 'in_size' parameter to cxl_payload_from_user_allowed() and validate\nthe payload is large enough.","publishedAt":"2026-03-25T10:27:19.815Z","updatedAt":"2026-10-30T12:23:55.930Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"c0874ca9282ccf5aeae559c697dd1feb577aad0e","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"3555e41737c0f8b5b53a511573661477e3942dee","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"483b7eb4b1b2a03235afe1b274732dcf8231d4ec","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"dc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"60b5d1f68338aff2c5af0113f04aefa7169c50c2","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":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","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":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","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/c0874ca9282ccf5aeae559c697dd1feb577aad0e","https://git.kernel.org/stable/c/3555e41737c0f8b5b53a511573661477e3942dee","https://git.kernel.org/stable/c/483b7eb4b1b2a03235afe1b274732dcf8231d4ec","https://git.kernel.org/stable/c/dc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61","https://git.kernel.org/stable/c/7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1","https://git.kernel.org/stable/c/60b5d1f68338aff2c5af0113f04aefa7169c50c2"],"weaknesses":[],"ingestedAt":"2026-10-30T12:40:04.423Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/23xxx/CVE-2026-23327.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-23327","state":"PUBLISHED","datePublished":"2026-03-25T10:27:19.815Z","dateUpdated":"2026-10-30T12:23:55.930Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-01-13T15:37:45.996Z"},"containers":{"cna":{"title":"cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()\n\ncxl_payload_from_user_allowed() casts and dereferences the input\npayload without first verifying its size. When a raw mailbox command\nis sent with an undersized payload (ie: 1 byte for CXL_MBOX_OP_CLEAR_LOG,\nwhich expects a 16-byte UUID), uuid_equal() reads past the allocated buffer,\ntriggering a KASAN splat:\n\nBUG: KASAN: slab-out-of-bounds in memcmp+0x176/0x1d0 lib/string.c:683\nRead of size 8 at addr ffff88810130f5c0 by task syz.1.62/2258\n\nCPU: 2 UID: 0 PID: 2258 Comm: syz.1.62 Not tainted 6.19.0-dirty #3 PREEMPT(voluntary)\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\nCall Trace:\n <TASK>\n __dump_stack lib/dump_stack.c:94 [inline]\n dump_stack_lvl+0xab/0xe0 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:378 [inline]\n print_report+0xce/0x650 mm/kasan/report.c:482\n kasan_report+0xce/0x100 mm/kasan/report.c:595\n memcmp+0x176/0x1d0 lib/string.c:683\n uuid_equal include/linux/uuid.h:73 [inline]\n cxl_payload_from_user_allowed drivers/cxl/core/mbox.c:345 [inline]\n cxl_mbox_cmd_ctor drivers/cxl/core/mbox.c:368 [inline]\n cxl_validate_cmd_from_user drivers/cxl/core/mbox.c:522 [inline]\n cxl_send_cmd+0x9c0/0xb50 drivers/cxl/core/mbox.c:643\n __cxl_memdev_ioctl drivers/cxl/core/memdev.c:698 [inline]\n cxl_memdev_ioctl+0x14f/0x190 drivers/cxl/core/memdev.c:713\n vfs_ioctl fs/ioctl.c:51 [inline]\n __do_sys_ioctl fs/ioctl.c:597 [inline]\n __se_sys_ioctl fs/ioctl.c:583 [inline]\n __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xa8/0x330 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7fdaf331ba79\nCode: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007fdaf1d77038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010\nRAX: ffffffffffffffda RBX: 00007fdaf3585fa0 RCX: 00007fdaf331ba79\nRDX: 00002000000001c0 RSI: 00000000c030ce02 RDI: 0000000000000003\nRBP: 00007fdaf33749df R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\nR13: 00007fdaf3586038 R14: 00007fdaf3585fa0 R15: 00007ffced2af768\n </TASK>\n\nAdd 'in_size' parameter to cxl_payload_from_user_allowed() and validate\nthe payload is large enough."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"c0874ca9282ccf5aeae559c697dd1feb577aad0e","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"3555e41737c0f8b5b53a511573661477e3942dee","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"483b7eb4b1b2a03235afe1b274732dcf8231d4ec","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"dc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1","versionType":"git"},{"version":"6179045ccc0c6229dc449afc1701dc7fbd40571f","status":"affected","lessThan":"60b5d1f68338aff2c5af0113f04aefa7169c50c2","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":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","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":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","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/c0874ca9282ccf5aeae559c697dd1feb577aad0e"},{"url":"https://git.kernel.org/stable/c/3555e41737c0f8b5b53a511573661477e3942dee"},{"url":"https://git.kernel.org/stable/c/483b7eb4b1b2a03235afe1b274732dcf8231d4ec"},{"url":"https://git.kernel.org/stable/c/dc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61"},{"url":"https://git.kernel.org/stable/c/7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1"},{"url":"https://git.kernel.org/stable/c/60b5d1f68338aff2c5af0113f04aefa7169c50c2"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:23:55.930Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.19.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}