{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43472", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:56.011Z", "datePublished": "2026-05-08T14:22:31.556Z", "dateUpdated": "2026-05-08T14:22:31.556Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-08T14:22:31.556Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nunshare: fix unshare_fs() handling\n\nThere's an unpleasant corner case in unshare(2), when we have a\nCLONE_NEWNS in flags and current->fs hadn't been shared at all; in that\ncase copy_mnt_ns() gets passed current->fs instead of a private copy,\nwhich causes interesting warts in proof of correctness]\n\n> I guess if private means fs->users == 1, the condition could still be true.\n\nUnfortunately, it's worse than just a convoluted proof of correctness.\nConsider the case when we have CLONE_NEWCGROUP in addition to CLONE_NEWNS\n(and current->fs->users == 1).\n\nWe pass current->fs to copy_mnt_ns(), all right. Suppose it succeeds and\nflips current->fs->{pwd,root} to corresponding locations in the new namespace.\nNow we proceed to copy_cgroup_ns(), which fails (e.g. with -ENOMEM).\nWe call put_mnt_ns() on the namespace created by copy_mnt_ns(), it's\ndestroyed and its mount tree is dissolved, but... current->fs->root and\ncurrent->fs->pwd are both left pointing to now detached mounts.\n\nThey are pinning those, so it's not a UAF, but it leaves the calling\nprocess with unshare(2) failing with -ENOMEM _and_ leaving it with\npwd and root on detached isolated mounts. The last part is clearly a bug.\n\nThere is other fun related to that mess (races with pivot_root(), including\nthe one between pivot_root() and fork(), of all things), but this one\nis easy to isolate and fix - treat CLONE_NEWNS as \"allocate a new\nfs_struct even if it hadn't been shared in the first place\". Sure, we could\ngo for something like \"if both CLONE_NEWNS *and* one of the things that might\nend up failing after copy_mnt_ns() call in create_new_namespaces() are set,\nforce allocation of new fs_struct\", but let's keep it simple - the cost\nof copy_fs_struct() is trivial.\n\nAnother benefit is that copy_mnt_ns() with CLONE_NEWNS *always* gets\na freshly allocated fs_struct, yet to be attached to anything. That\nseriously simplifies the analysis...\n\nFWIW, that bug had been there since the introduction of unshare(2) ;-/"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/fork.c"], "versions": [{"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "845bf3c6963a52096d0d3866e4a92db77a0c03d8", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "d3ffc8f13034af895531a02c30b1fe3a34b46432", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "d0d99f60538ddb4a62ccaac2168d8f448965f083", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "d7963d6997fea86a6def242ac36198b86655f912", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "aa9ebc084505fb26dd90f4d7a249045aad152043", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "af8f4be3b68ac8caa41c8e5ead0eeaf5e85e42d0", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "42e21e74061b0ebbd859839f81acf10efad02a27", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "6c4b2243cb6c0755159bd567130d5e12e7b10d9f", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/fork.c"], "versions": [{"version": "5.10.253", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.167", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.130", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.78", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.19", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19.9", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.10.253"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.15.203"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.1.167"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.6.130"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.12.78"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.18.19"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.19.9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "7.0"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/845bf3c6963a52096d0d3866e4a92db77a0c03d8"}, {"url": "https://git.kernel.org/stable/c/d3ffc8f13034af895531a02c30b1fe3a34b46432"}, {"url": "https://git.kernel.org/stable/c/d0d99f60538ddb4a62ccaac2168d8f448965f083"}, {"url": "https://git.kernel.org/stable/c/d7963d6997fea86a6def242ac36198b86655f912"}, {"url": "https://git.kernel.org/stable/c/aa9ebc084505fb26dd90f4d7a249045aad152043"}, {"url": "https://git.kernel.org/stable/c/af8f4be3b68ac8caa41c8e5ead0eeaf5e85e42d0"}, {"url": "https://git.kernel.org/stable/c/42e21e74061b0ebbd859839f81acf10efad02a27"}, {"url": "https://git.kernel.org/stable/c/6c4b2243cb6c0755159bd567130d5e12e7b10d9f"}], "title": "unshare: fix unshare_fs() handling", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nunshare: fix unshare_fs() handling\n\nThere's an unpleasant corner case in unshare(2), when we have a\nCLONE_NEWNS in flags and current->fs hadn't been shared at all; in that\ncase copy_mnt_ns() gets passed current->fs instead of a private copy,\nwhich causes interesting warts in proof of correctness]\n\n> I guess if private means fs->users == 1, the condition could still be true.\n\nUnfortunately, it's worse than just a convoluted proof of correctness.\nConsider the case when we have CLONE_NEWCGROUP in addition to CLONE_NEWNS\n(and current->fs->users == 1).\n\nWe pass current->fs to copy_mnt_ns(), all right. Suppose it succeeds and\nflips current->fs->{pwd,root} to corresponding locations in the new namespace.\nNow we proceed to copy_cgroup_ns(), which fails (e.g. with -ENOMEM).\nWe call put_mnt_ns() on the namespace created by copy_mnt_ns(), it's\ndestroyed and its mount tree is dissolved, but... current->fs->root and\ncurrent->fs->pwd are both left pointing to now detached mounts.\n\nThey are pinning those, so it's not a UAF, but it leaves the calling\nprocess with unshare(2) failing with -ENOMEM _and_ leaving it with\npwd and root on detached isolated mounts. The last part is clearly a bug.\n\nThere is other fun related to that mess (races with pivot_root(), including\nthe one between pivot_root() and fork(), of all things), but this one\nis easy to isolate and fix - treat CLONE_NEWNS as \"allocate a new\nfs_struct even if it hadn't been shared in the first place\". Sure, we could\ngo for something like \"if both CLONE_NEWNS *and* one of the things that might\nend up failing after copy_mnt_ns() call in create_new_namespaces() are set,\nforce allocation of new fs_struct\", but let's keep it simple - the cost\nof copy_fs_struct() is trivial.\n\nAnother benefit is that copy_mnt_ns() with CLONE_NEWNS *always* gets\na freshly allocated fs_struct, yet to be attached to anything. That\nseriously simplifies the analysis...\n\nFWIW, that bug had been there since the introduction of unshare(2) ;-/"}], "id": "CVE-2026-43472", "lastModified": "2026-05-08T15:17:00.313", "metrics": {}, "published": "2026-05-08T15:17:00.313", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/42e21e74061b0ebbd859839f81acf10efad02a27"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6c4b2243cb6c0755159bd567130d5e12e7b10d9f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/845bf3c6963a52096d0d3866e4a92db77a0c03d8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/aa9ebc084505fb26dd90f4d7a249045aad152043"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/af8f4be3b68ac8caa41c8e5ead0eeaf5e85e42d0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d0d99f60538ddb4a62ccaac2168d8f448965f083"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d3ffc8f13034af895531a02c30b1fe3a34b46432"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d7963d6997fea86a6def242ac36198b86655f912"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{}