{"id":"CVE-2026-63810","state":"PUBLISHED","title":"block: Avoid mounting the bdev pseudo-filesystem in userspace","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nblock: Avoid mounting the bdev pseudo-filesystem in userspace\n\nThe bdev pseudo-filesystem is an internal kernel filesystem with which\nuserspace should not interfere. Unregister it so that userspace cannot\neven attempt to mount it.\n\nThis fixes a bug [1] that occurs when attempting to access files,\nbecause the system call move_mount() uses pointers declared in the\ninode_operations structure, which for the bdev pseudo-filesystem\nare always equal to 0. `inode->i_op = &empty_iops;`\n\n[1]\n\n BUG: kernel NULL pointer dereference, address: 0000000000000000\n #PF: supervisor instruction fetch in kernel mode\n #PF: error_code(0x0010) - not-present page\n PGD 23380067 P4D 23380067 PUD 23381067 PMD 0\n Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI\n CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014\n RIP: 0010:0x0\n\n Call Trace:\n <TASK>\n lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460\n open_last_lookups fs/namei.c:3550 [inline]\n path_openat+0x953/0x2700 fs/namei.c:3780\n do_filp_open+0x1c5/0x410 fs/namei.c:3810\n do_sys_openat2+0x171/0x4d0 fs/open.c:1318\n do_sys_open fs/open.c:1334 [inline]\n __do_sys_openat fs/open.c:1350 [inline]\n __se_sys_openat fs/open.c:1345 [inline]\n __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345\n do_syscall_x64 arch/x86/entry/common.c:51 [inline]\n do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81\n entry_SYSCALL_64_after_hwframe+0x6e/0xd8\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller.","publishedAt":"2026-07-19T12:02:12.484Z","updatedAt":"2026-10-15T01:23:32.309Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3d3fcf23993bb756de2f912ab631cfdcc4746554","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"99cde0a7b1e98fd3970aabef1300918e91698dd5","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"1a02a5028bd6dead1f8503854ef3168d651cd417","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"197971e6ffc0a6356b2ba2b22beb42bc0f7e412d","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3804e6de30ae7b053d53341d9d6944356cf23b40","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"717f721eb67d2dacd3ed5f7495aef2f442e84ce4","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"f73aa66dffcb8e61e78f01b56163ec16a15d06d2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/bdev.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","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":["block/bdev.c"]}],"references":["https://git.kernel.org/stable/c/3d3fcf23993bb756de2f912ab631cfdcc4746554","https://git.kernel.org/stable/c/99cde0a7b1e98fd3970aabef1300918e91698dd5","https://git.kernel.org/stable/c/1a02a5028bd6dead1f8503854ef3168d651cd417","https://git.kernel.org/stable/c/197971e6ffc0a6356b2ba2b22beb42bc0f7e412d","https://git.kernel.org/stable/c/3804e6de30ae7b053d53341d9d6944356cf23b40","https://git.kernel.org/stable/c/717f721eb67d2dacd3ed5f7495aef2f442e84ce4","https://git.kernel.org/stable/c/f73aa66dffcb8e61e78f01b56163ec16a15d06d2","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63810.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63810","state":"PUBLISHED","datePublished":"2026-07-19T12:02:12.484Z","dateUpdated":"2026-10-15T01:23:32.309Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.013Z"},"containers":{"cna":{"title":"block: Avoid mounting the bdev pseudo-filesystem in userspace","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nblock: Avoid mounting the bdev pseudo-filesystem in userspace\n\nThe bdev pseudo-filesystem is an internal kernel filesystem with which\nuserspace should not interfere. Unregister it so that userspace cannot\neven attempt to mount it.\n\nThis fixes a bug [1] that occurs when attempting to access files,\nbecause the system call move_mount() uses pointers declared in the\ninode_operations structure, which for the bdev pseudo-filesystem\nare always equal to 0. `inode->i_op = &empty_iops;`\n\n[1]\n\n BUG: kernel NULL pointer dereference, address: 0000000000000000\n #PF: supervisor instruction fetch in kernel mode\n #PF: error_code(0x0010) - not-present page\n PGD 23380067 P4D 23380067 PUD 23381067 PMD 0\n Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI\n CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014\n RIP: 0010:0x0\n\n Call Trace:\n <TASK>\n lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460\n open_last_lookups fs/namei.c:3550 [inline]\n path_openat+0x953/0x2700 fs/namei.c:3780\n do_filp_open+0x1c5/0x410 fs/namei.c:3810\n do_sys_openat2+0x171/0x4d0 fs/open.c:1318\n do_sys_open fs/open.c:1334 [inline]\n __do_sys_openat fs/open.c:1350 [inline]\n __se_sys_openat fs/open.c:1345 [inline]\n __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345\n do_syscall_x64 arch/x86/entry/common.c:51 [inline]\n do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81\n entry_SYSCALL_64_after_hwframe+0x6e/0xd8\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3d3fcf23993bb756de2f912ab631cfdcc4746554","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"99cde0a7b1e98fd3970aabef1300918e91698dd5","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"1a02a5028bd6dead1f8503854ef3168d651cd417","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"197971e6ffc0a6356b2ba2b22beb42bc0f7e412d","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3804e6de30ae7b053d53341d9d6944356cf23b40","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"717f721eb67d2dacd3ed5f7495aef2f442e84ce4","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"f73aa66dffcb8e61e78f01b56163ec16a15d06d2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/bdev.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","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":["block/bdev.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/3d3fcf23993bb756de2f912ab631cfdcc4746554"},{"url":"https://git.kernel.org/stable/c/99cde0a7b1e98fd3970aabef1300918e91698dd5"},{"url":"https://git.kernel.org/stable/c/1a02a5028bd6dead1f8503854ef3168d651cd417"},{"url":"https://git.kernel.org/stable/c/197971e6ffc0a6356b2ba2b22beb42bc0f7e412d"},{"url":"https://git.kernel.org/stable/c/3804e6de30ae7b053d53341d9d6944356cf23b40"},{"url":"https://git.kernel.org/stable/c/717f721eb67d2dacd3ed5f7495aef2f442e84ce4"},{"url":"https://git.kernel.org/stable/c/f73aa66dffcb8e61e78f01b56163ec16a15d06d2"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:51:16.632Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.95"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.1.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"vendor":"Siemens","product":"SIMATIC 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