{"api_version":"1","generated_at":"2026-08-03T21:53:06+00:00","cve":"CVE-2026-64294","urls":{"html":"https://cve.report/CVE-2026-64294","api":"https://cve.report/api/cve/CVE-2026-64294.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64294","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64294"},"summary":{"title":"mm: do file ownership checks with the proper mount idmap","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: do file ownership checks with the proper mount idmap\n\nEver since idmapped mounts were introduced, inode ownership checks (for\nside-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done\nagainst the nop_mnt_idmap, which completely ignores the file's mount's\nidmap.  This results in odd edgecases like:\n\n1) mount/bind-mount with an idmap userA:userB:1\n2) userB runs an owner_or_capable() check on file that is owned by userA\non-disk/in-memory, but owned by userB after idmap translation\n3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied\n\nIn the case of mincore/madvise MADV_PAGEOUT, this is usually benign,\nbecause file_permission(file, MAY_WRITE) will probably succeed, as it uses\nthe proper idmap internally, but it does not need to be the case on e.g a\n0444 file where even the owner itself doesn't have permissions to write to\nit.\n\nSince this is clearly not trivial to get right, introduce a\nfile_owner_or_capable() that can carry the correct semantics, and switch\nthe various users in mm to it.\n\nThe issue was found by manual code inspection & an off-list discussion\nwith Jan Kara.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-25 10:17:10","updated_at":"2026-07-30 15:00:27"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/5c942ad7df75925ee166e7f0fb36892d8dde376b","name":"https://git.kernel.org/stable/c/5c942ad7df75925ee166e7f0fb36892d8dde376b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8344bdf0629457e532797b42d9d2bbf2a2900bbf","name":"https://git.kernel.org/stable/c/8344bdf0629457e532797b42d9d2bbf2a2900bbf","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/04ba248d02d9eaa3d9077b00a6134caa75fa3e90","name":"https://git.kernel.org/stable/c/04ba248d02d9eaa3d9077b00a6134caa75fa3e90","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e187bc02f8fa4226d62814592cf064ee4557c470","name":"https://git.kernel.org/stable/c/e187bc02f8fa4226d62814592cf064ee4557c470","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/744b23aa430d52f5c8e4dbff7d71496d6643bed2","name":"https://git.kernel.org/stable/c/744b23aa430d52f5c8e4dbff7d71496d6643bed2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64294","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64294","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9caccd41541a6f7d6279928d9f971f6642c361af 744b23aa430d52f5c8e4dbff7d71496d6643bed2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9caccd41541a6f7d6279928d9f971f6642c361af 8344bdf0629457e532797b42d9d2bbf2a2900bbf git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9caccd41541a6f7d6279928d9f971f6642c361af 5c942ad7df75925ee166e7f0fb36892d8dde376b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9caccd41541a6f7d6279928d9f971f6642c361af 04ba248d02d9eaa3d9077b00a6134caa75fa3e90 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9caccd41541a6f7d6279928d9f971f6642c361af e187bc02f8fa4226d62814592cf064ee4557c470 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.12","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.12 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.145 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.96 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.39 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.4 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"64294","cve":"CVE-2026-64294","epss":"0.002000000","percentile":"0.100790000","score_date":"2026-08-02","updated_at":"2026-08-03 00:14:24"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/linux/fs.h","mm/filemap.c","mm/madvise.c","mm/mincore.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"744b23aa430d52f5c8e4dbff7d71496d6643bed2","status":"affected","version":"9caccd41541a6f7d6279928d9f971f6642c361af","versionType":"git"},{"lessThan":"8344bdf0629457e532797b42d9d2bbf2a2900bbf","status":"affected","version":"9caccd41541a6f7d6279928d9f971f6642c361af","versionType":"git"},{"lessThan":"5c942ad7df75925ee166e7f0fb36892d8dde376b","status":"affected","version":"9caccd41541a6f7d6279928d9f971f6642c361af","versionType":"git"},{"lessThan":"04ba248d02d9eaa3d9077b00a6134caa75fa3e90","status":"affected","version":"9caccd41541a6f7d6279928d9f971f6642c361af","versionType":"git"},{"lessThan":"e187bc02f8fa4226d62814592cf064ee4557c470","status":"affected","version":"9caccd41541a6f7d6279928d9f971f6642c361af","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/linux/fs.h","mm/filemap.c","mm/madvise.c","mm/mincore.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.12"},{"lessThan":"5.12","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.145","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.96","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.39","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.145","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.96","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.39","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.4","versionStartIncluding":"5.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc3","versionStartIncluding":"5.12","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: do file ownership checks with the proper mount idmap\n\nEver since idmapped mounts were introduced, inode ownership checks (for\nside-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done\nagainst the nop_mnt_idmap, which completely ignores the file's mount's\nidmap.  This results in odd edgecases like:\n\n1) mount/bind-mount with an idmap userA:userB:1\n2) userB runs an owner_or_capable() check on file that is owned by userA\non-disk/in-memory, but owned by userB after idmap translation\n3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied\n\nIn the case of mincore/madvise MADV_PAGEOUT, this is usually benign,\nbecause file_permission(file, MAY_WRITE) will probably succeed, as it uses\nthe proper idmap internally, but it does not need to be the case on e.g a\n0444 file where even the owner itself doesn't have permissions to write to\nit.\n\nSince this is clearly not trivial to get right, introduce a\nfile_owner_or_capable() that can carry the correct semantics, and switch\nthe various users in mm to it.\n\nThe issue was found by manual code inspection & an off-list discussion\nwith Jan Kara."}],"providerMetadata":{"dateUpdated":"2026-07-25T08:49:32.570Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/744b23aa430d52f5c8e4dbff7d71496d6643bed2"},{"url":"https://git.kernel.org/stable/c/8344bdf0629457e532797b42d9d2bbf2a2900bbf"},{"url":"https://git.kernel.org/stable/c/5c942ad7df75925ee166e7f0fb36892d8dde376b"},{"url":"https://git.kernel.org/stable/c/04ba248d02d9eaa3d9077b00a6134caa75fa3e90"},{"url":"https://git.kernel.org/stable/c/e187bc02f8fa4226d62814592cf064ee4557c470"}],"title":"mm: do file ownership checks with the proper mount idmap","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64294","datePublished":"2026-07-25T08:49:32.570Z","dateReserved":"2026-07-19T15:36:31.778Z","dateUpdated":"2026-07-25T08:49:32.570Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-25 10:17:10","lastModifiedDate":"2026-07-30 15:00:27","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64294","Ordinal":"1","Title":"mm: do file ownership checks with the proper mount idmap","CVE":"CVE-2026-64294","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64294","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: do file ownership checks with the proper mount idmap\n\nEver since idmapped mounts were introduced, inode ownership checks (for\nside-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done\nagainst the nop_mnt_idmap, which completely ignores the file's mount's\nidmap.  This results in odd edgecases like:\n\n1) mount/bind-mount with an idmap userA:userB:1\n2) userB runs an owner_or_capable() check on file that is owned by userA\non-disk/in-memory, but owned by userB after idmap translation\n3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied\n\nIn the case of mincore/madvise MADV_PAGEOUT, this is usually benign,\nbecause file_permission(file, MAY_WRITE) will probably succeed, as it uses\nthe proper idmap internally, but it does not need to be the case on e.g a\n0444 file where even the owner itself doesn't have permissions to write to\nit.\n\nSince this is clearly not trivial to get right, introduce a\nfile_owner_or_capable() that can carry the correct semantics, and switch\nthe various users in mm to it.\n\nThe issue was found by manual code inspection & an off-list discussion\nwith Jan Kara.","Type":"Description","Title":"mm: do file ownership checks with the proper mount idmap"}]}}}