{"api_version":"1","generated_at":"2026-04-23T09:41:32+00:00","cve":"CVE-2026-23225","urls":{"html":"https://cve.report/CVE-2026-23225","api":"https://cve.report/api/cve/CVE-2026-23225.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-23225","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-23225"},"summary":{"title":"sched/mmcid: Don't assume CID is CPU owned on mode switch","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/mmcid: Don't assume CID is CPU owned on mode switch\n\nShinichiro reported a KASAN UAF, which is actually an out of bounds access\nin the MMCID management code.\n\n   CPU0\t\t\t\t\t\tCPU1\n   \t\t\t\t\t\tT1 runs in userspace\n   T0: fork(T4) -> Switch to per CPU CID mode\n         fixup() set MM_CID_TRANSIT on T1/CPU1\n   T4 exit()\n   T3 exit()\n   T2 exit()\n\t\t\t\t\t\tT1 exit() switch to per task mode\n\t\t\t\t\t\t ---> Out of bounds access.\n\nAs T1 has not scheduled after T0 set the TRANSIT bit, it exits with the\nTRANSIT bit set. sched_mm_cid_remove_user() clears the TRANSIT bit in\nthe task and drops the CID, but it does not touch the per CPU storage.\nThat's functionally correct because a CID is only owned by the CPU when\nthe ONCPU bit is set, which is mutually exclusive with the TRANSIT flag.\n\nNow sched_mm_cid_exit() assumes that the CID is CPU owned because the\nprior mode was per CPU. It invokes mm_drop_cid_on_cpu() which clears the\nnot set ONCPU bit and then invokes clear_bit() with an insanely large\nbit number because TRANSIT is set (bit 29).\n\nPrevent that by actually validating that the CID is CPU owned in\nmm_drop_cid_on_cpu().","state":"PUBLISHED","assigner":"Linux","published_at":"2026-02-18 16:22:32","updated_at":"2026-04-02 15:16:23"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/81f29975631db8a78651b3140ecd0f88ffafc476","name":"https://git.kernel.org/stable/c/81f29975631db8a78651b3140ecd0f88ffafc476","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1e83ccd5921a610ef409a7d4e56db27822b4ea39","name":"https://git.kernel.org/stable/c/1e83ccd5921a610ef409a7d4e56db27822b4ea39","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-23225","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23225","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 007d84287c7466ca68a5809b616338214dc5b77b 81f29975631db8a78651b3140ecd0f88ffafc476 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 007d84287c7466ca68a5809b616338214dc5b77b 1e83ccd5921a610ef409a7d4e56db27822b4ea39 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.19","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.1 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"23225","cve":"CVE-2026-23225","epss":"0.000170000","percentile":"0.039470000","score_date":"2026-04-07","updated_at":"2026-04-08 00:03:40"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["kernel/sched/core.c","kernel/sched/sched.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"81f29975631db8a78651b3140ecd0f88ffafc476","status":"affected","version":"007d84287c7466ca68a5809b616338214dc5b77b","versionType":"git"},{"lessThan":"1e83ccd5921a610ef409a7d4e56db27822b4ea39","status":"affected","version":"007d84287c7466ca68a5809b616338214dc5b77b","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["kernel/sched/core.c","kernel/sched/sched.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.19"},{"lessThan":"6.19","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.1","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.0-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.1","versionStartIncluding":"6.19","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0-rc1","versionStartIncluding":"6.19","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/mmcid: Don't assume CID is CPU owned on mode switch\n\nShinichiro reported a KASAN UAF, which is actually an out of bounds access\nin the MMCID management code.\n\n   CPU0\t\t\t\t\t\tCPU1\n   \t\t\t\t\t\tT1 runs in userspace\n   T0: fork(T4) -> Switch to per CPU CID mode\n         fixup() set MM_CID_TRANSIT on T1/CPU1\n   T4 exit()\n   T3 exit()\n   T2 exit()\n\t\t\t\t\t\tT1 exit() switch to per task mode\n\t\t\t\t\t\t ---> Out of bounds access.\n\nAs T1 has not scheduled after T0 set the TRANSIT bit, it exits with the\nTRANSIT bit set. sched_mm_cid_remove_user() clears the TRANSIT bit in\nthe task and drops the CID, but it does not touch the per CPU storage.\nThat's functionally correct because a CID is only owned by the CPU when\nthe ONCPU bit is set, which is mutually exclusive with the TRANSIT flag.\n\nNow sched_mm_cid_exit() assumes that the CID is CPU owned because the\nprior mode was per CPU. It invokes mm_drop_cid_on_cpu() which clears the\nnot set ONCPU bit and then invokes clear_bit() with an insanely large\nbit number because TRANSIT is set (bit 29).\n\nPrevent that by actually validating that the CID is CPU owned in\nmm_drop_cid_on_cpu()."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-04-02T14:43:46.344Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/81f29975631db8a78651b3140ecd0f88ffafc476"},{"url":"https://git.kernel.org/stable/c/1e83ccd5921a610ef409a7d4e56db27822b4ea39"}],"title":"sched/mmcid: Don't assume CID is CPU owned on mode switch","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-23225","datePublished":"2026-02-18T14:53:28.387Z","dateReserved":"2026-01-13T15:37:45.987Z","dateUpdated":"2026-04-02T14:43:46.344Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-02-18 16:22:32","lastModifiedDate":"2026-04-02 15:16:23","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"23225","Ordinal":"1","Title":"sched/mmcid: Don't assume CID is CPU owned on mode switch","CVE":"CVE-2026-23225","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"23225","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/mmcid: Don't assume CID is CPU owned on mode switch\n\nShinichiro reported a KASAN UAF, which is actually an out of bounds access\nin the MMCID management code.\n\n   CPU0\t\t\t\t\t\tCPU1\n   \t\t\t\t\t\tT1 runs in userspace\n   T0: fork(T4) -> Switch to per CPU CID mode\n         fixup() set MM_CID_TRANSIT on T1/CPU1\n   T4 exit()\n   T3 exit()\n   T2 exit()\n\t\t\t\t\t\tT1 exit() switch to per task mode\n\t\t\t\t\t\t ---> Out of bounds access.\n\nAs T1 has not scheduled after T0 set the TRANSIT bit, it exits with the\nTRANSIT bit set. sched_mm_cid_remove_user() clears the TRANSIT bit in\nthe task and drops the CID, but it does not touch the per CPU storage.\nThat's functionally correct because a CID is only owned by the CPU when\nthe ONCPU bit is set, which is mutually exclusive with the TRANSIT flag.\n\nNow sched_mm_cid_exit() assumes that the CID is CPU owned because the\nprior mode was per CPU. It invokes mm_drop_cid_on_cpu() which clears the\nnot set ONCPU bit and then invokes clear_bit() with an insanely large\nbit number because TRANSIT is set (bit 29).\n\nPrevent that by actually validating that the CID is CPU owned in\nmm_drop_cid_on_cpu().","Type":"Description","Title":"sched/mmcid: Don't assume CID is CPU owned on mode switch"}]}}}