{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-43472", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-43472", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-05-08T14:22:31.556Z", "updatedAt": "2026-05-11T22:25:16.258Z", "importedAt": "2026-10-24T01:58:14.884Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "unshare: fix unshare_fs() handling", "summary": "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": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "741a295130606143edbf9fc740f633dbc1e6225f", "status": "affected", "versionType": "git", "lessThan": "845bf3c6963a52096d0d3866e4a92db77a0c03d8" }, { "version": "741a295130606143edbf9fc740f633dbc1e6225f", "status": "affected", "versionType": "git", "lessThan": "d3ffc8f13034af895531a02c30b1fe3a34b46432" }, { "version": "741a295130606143edbf9fc740f633dbc1e6225f", "status": "affected", "versionType": "git", "lessThan": "d0d99f60538ddb4a62ccaac2168d8f448965f083" }, { "version": "741a295130606143edbf9fc740f633dbc1e6225f", "status": "affected", "versionType": "git", "lessThan": "d7963d6997fea86a6def242ac36198b86655f912" }, { "version": "741a295130606143edbf9fc740f633dbc1e6225f", "status": "affected", "versionType": "git", "lessThan": "aa9ebc084505fb26dd90f4d7a249045aad152043" }, { "version": "741a295130606143edbf9fc740f633dbc1e6225f", "status": "affected", "versionType": "git", "lessThan": "af8f4be3b68ac8caa41c8e5ead0eeaf5e85e42d0" }, { "version": "741a295130606143edbf9fc740f633dbc1e6225f", "status": "affected", "versionType": "git", "lessThan": "42e21e74061b0ebbd859839f81acf10efad02a27" }, { "version": "741a295130606143edbf9fc740f633dbc1e6225f", "status": "affected", "versionType": "git", "lessThan": "6c4b2243cb6c0755159bd567130d5e12e7b10d9f" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "2.6.16", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "2.6.16" }, { "version": "5.10.253", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.203", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.167", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.130", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.78", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.19", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "6.19.9", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.19.*" }, { "version": "7.0", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }