{"id":"CVE-2026-98215","revision":"1abfb119c77842b2a37262e818f1981c","records":[{"revision":"1abfb119c77842b2a37262e818f1981c","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98215","aliases":[],"title":"selinux: preserve user SID across nested backing files","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nselinux: preserve user SID across nested backing files\n\nSELinux saves the user file SID in a backing-file security blob so it\nremains available after mmap() replaces vma->vm_file with a backing file.\n\nFor nested backing files (overlayfs over overlayfs, or FUSE passthrough\nbacked by overlayfs), user_file may itself be a backing file.  Its\nfsec->sid is the SID of the mounter that opened it, rather than the user\nthat opened the top-level file.  mprotect() then checks fd { use } against\nthe mounter SID.  This can incorrectly deny access without a domain\ntransition, or check the wrong target SID after one.\n\nCopy the saved user SID when user_file is a backing file.  Keep using the\nregular file SID for the first backing layer.\n\nWith two nested overlayfs mounts and SELinux enforcing,\nmprotect(PROT_READ) returns EACCES with an fd { use } denial against the\nmounter SID.  With this change, mprotect() succeeds.\n\nTested on arm64 QEMU with a small BusyBox initramfs and a purpose-built\nSELinux policy.  The original test was also repeated with Fedora Cloud\nBase 44 userspace and gave the same result.","state":0,"publishedAt":"2026-10-06T08:44:51.412+00:00","modifiedAt":"2026-10-19T09:15:46.038+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"security/selinux/hooks.c\",\n                        \"security/selinux/include/objsec.h\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"bc6c380c1159de52a252ed11f19a42c47f60a735\",\n                            \"lessThan\": \"caa1b913d90d5dc07073733326d2af0f0288f089\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8bacd09f12c27710228562e4d13163e58c5f4a45\",\n                            \"lessThan\": \"6aaeec59aadcd1eafc18b049f1b759fb6b9d9569\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d844702198395d3f80222777030f69db6be6b709\",\n                            \"lessThan\": \"9d99b770e7b67b00bdef9005b928aad13e1d679b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"82544d36b1729153c8aeb179e84750f0c085d3b1\",\n                            \"lessThan\": \"ff20d16b2e8230c034e21540043df47222dcc09b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"82544d36b1729153c8aeb179e84750f0c085d3b1\",\n                            \"lessThan\": \"8c0c602202b9a4909b00bc3354e3c0355bc69e65\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"cd0e707a927a70cdfd8bc5a512a9719a87f5ed51\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"6.6.144\",\n                            \"lessThan\": \"6.6.158\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.95\",\n                            \"lessThan\": \"6.12.112\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.38\",\n                            \"lessThan\": \"6.18.54\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0.4\",\n                            \"lessThan\": \"7.1\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"security/selinux/hooks.c\",\n                        \"security/selinux/include/objsec.h\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"7.1\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"7.1\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.158\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.112\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.54\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.8\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/caa1b913d90d5dc07073733326d2af0f0288f089","https://git.kernel.org/stable/c/6aaeec59aadcd1eafc18b049f1b759fb6b9d9569","https://git.kernel.org/stable/c/9d99b770e7b67b00bdef9005b928aad13e1d679b","https://git.kernel.org/stable/c/ff20d16b2e8230c034e21540043df47222dcc09b","https://git.kernel.org/stable/c/8c0c602202b9a4909b00bc3354e3c0355bc69e65"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98215","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98215","identifiers":["CVE-2026-98215"]},"retained":false,"historicalAffected":[]}],"coverage":[]}