{"api_version":"1","generated_at":"2026-11-01T09:40:57+00:00","cve":"CVE-2026-99173","urls":{"html":"https://cve.report/CVE-2026-99173","api":"https://cve.report/api/cve/CVE-2026-99173.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99173","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99173"},"summary":{"title":"eventfs: Free the eventfs_inode after an rcu grace period too","description":"In the Linux kernel, the following vulnerability has been resolved:\n\neventfs: Free the eventfs_inode after an rcu grace period too\n\ntracefs_d_revalidate() reads ->is_freed of the eventfs_inode that\ndentry->d_fsdata points to, and ->d_revalidate() is called in rcu\npathwalk mode with nothing but rcu_read_lock() held. The dentry itself\nstays around for such a walker, but tracefs_d_release() drops its\nreference to the eventfs_inode when the dentry is killed, and\nrelease_ei() then frees it after a grace period of eventfs_srcu. An\nSRCU grace period doesn't wait for rcu_read_lock() sections, so the\nwalker can read an eventfs_inode that is already gone.\n\nWith a pathwalk held up in tracefs_d_revalidate() while the dentry goes\naway:\n\n  BUG: KASAN: slab-use-after-free in tracefs_d_revalidate+0x76/0x90\n  Read of size 1 at addr ff1100010152d8d0 by task walker/97\n  Call Trace:\n   <TASK>\n   tracefs_d_revalidate+0x76/0x90\n   lookup_fast+0x320/0x640\n   path_lookupat+0x160/0xb00\n   filename_lookup+0x1f1/0x5b0\n   vfs_statx+0xd7/0x3b0\n   vfs_fstatat+0x4d/0x90\n   __do_sys_newfstatat+0xa0/0x100\n   do_syscall_64+0x10e/0x5e0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  [...]\n  Allocated by task 1:\n   __kmalloc_cache_noprof+0x249/0x560\n   eventfs_create_dir+0x7a/0x590\n   event_create_dir+0x2fb/0xcf0\n   trace_add_event_call+0xbf/0x150\n  [...]\n  Freed by task 11:\n   kfree+0x1db/0x5b0\n   srcu_invoke_callbacks+0x3a3/0x620\n   process_one_work+0x937/0x1810\n   worker_thread+0x4f1/0xd60\n\nBefore commit 8e556432477e (\"eventfs: Use SRCU for freeing\neventfs_inodes\") release_ei() used call_rcu(), which covered the walker,\nwhile eventfs_iterate() needs the SRCU grace period. Wait for both and\nchain call_rcu() from the SRCU callback.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-28 11:17:37","updated_at":"2026-10-31 13:17:58"},"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/5819018dc29fb2ac2fd4865d507f9893c89c0624","name":"https://git.kernel.org/stable/c/5819018dc29fb2ac2fd4865d507f9893c89c0624","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/45fcfd5d9c10e0aa977ed5b9bd445707e01bb107","name":"https://git.kernel.org/stable/c/45fcfd5d9c10e0aa977ed5b9bd445707e01bb107","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2cd88c498ecff8e22bf4c397b8eb226db70ac343","name":"https://git.kernel.org/stable/c/2cd88c498ecff8e22bf4c397b8eb226db70ac343","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dd2c767814a876be0f16f0b7f98a403dc176f51e","name":"https://git.kernel.org/stable/c/dd2c767814a876be0f16f0b7f98a403dc176f51e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4586ef24ce390e8becb9f3e5852d5d3978b01c33","name":"https://git.kernel.org/stable/c/4586ef24ce390e8becb9f3e5852d5d3978b01c33","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99173","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99173","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2ef3d120d19faba3dec35b10a025b00db0284373 5819018dc29fb2ac2fd4865d507f9893c89c0624 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8e556432477e97ad6179c61b61a32bf5f1af2355 dd2c767814a876be0f16f0b7f98a403dc176f51e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8e556432477e97ad6179c61b61a32bf5f1af2355 4586ef24ce390e8becb9f3e5852d5d3978b01c33 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8e556432477e97ad6179c61b61a32bf5f1af2355 45fcfd5d9c10e0aa977ed5b9bd445707e01bb107 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8e556432477e97ad6179c61b61a32bf5f1af2355 2cd88c498ecff8e22bf4c397b8eb226db70ac343 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 384f383c5aa7bfd619d9f56a513a36e533428186 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.46 6.6.161 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.10.5 6.11 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.11","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.11 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.161 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.115 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.59 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.13 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"99173","cve":"CVE-2026-99173","epss":"0.001680000","percentile":"0.061690000","score_date":"2026-10-31","updated_at":"2026-11-01 00:01:49"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/tracefs/event_inode.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"5819018dc29fb2ac2fd4865d507f9893c89c0624","status":"affected","version":"2ef3d120d19faba3dec35b10a025b00db0284373","versionType":"git"},{"lessThan":"dd2c767814a876be0f16f0b7f98a403dc176f51e","status":"affected","version":"8e556432477e97ad6179c61b61a32bf5f1af2355","versionType":"git"},{"lessThan":"4586ef24ce390e8becb9f3e5852d5d3978b01c33","status":"affected","version":"8e556432477e97ad6179c61b61a32bf5f1af2355","versionType":"git"},{"lessThan":"45fcfd5d9c10e0aa977ed5b9bd445707e01bb107","status":"affected","version":"8e556432477e97ad6179c61b61a32bf5f1af2355","versionType":"git"},{"lessThan":"2cd88c498ecff8e22bf4c397b8eb226db70ac343","status":"affected","version":"8e556432477e97ad6179c61b61a32bf5f1af2355","versionType":"git"},{"status":"affected","version":"384f383c5aa7bfd619d9f56a513a36e533428186","versionType":"git"},{"lessThan":"6.6.161","status":"affected","version":"6.6.46","versionType":"semver"},{"lessThan":"6.11","status":"affected","version":"6.10.5","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/tracefs/event_inode.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.11"},{"lessThan":"6.11","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.161","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.115","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.59","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.13","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.161","versionStartIncluding":"6.6.46","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.115","versionStartIncluding":"6.11","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.59","versionStartIncluding":"6.11","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.13","versionStartIncluding":"6.11","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"6.11","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10.5","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\neventfs: Free the eventfs_inode after an rcu grace period too\n\ntracefs_d_revalidate() reads ->is_freed of the eventfs_inode that\ndentry->d_fsdata points to, and ->d_revalidate() is called in rcu\npathwalk mode with nothing but rcu_read_lock() held. The dentry itself\nstays around for such a walker, but tracefs_d_release() drops its\nreference to the eventfs_inode when the dentry is killed, and\nrelease_ei() then frees it after a grace period of eventfs_srcu. An\nSRCU grace period doesn't wait for rcu_read_lock() sections, so the\nwalker can read an eventfs_inode that is already gone.\n\nWith a pathwalk held up in tracefs_d_revalidate() while the dentry goes\naway:\n\n  BUG: KASAN: slab-use-after-free in tracefs_d_revalidate+0x76/0x90\n  Read of size 1 at addr ff1100010152d8d0 by task walker/97\n  Call Trace:\n   <TASK>\n   tracefs_d_revalidate+0x76/0x90\n   lookup_fast+0x320/0x640\n   path_lookupat+0x160/0xb00\n   filename_lookup+0x1f1/0x5b0\n   vfs_statx+0xd7/0x3b0\n   vfs_fstatat+0x4d/0x90\n   __do_sys_newfstatat+0xa0/0x100\n   do_syscall_64+0x10e/0x5e0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  [...]\n  Allocated by task 1:\n   __kmalloc_cache_noprof+0x249/0x560\n   eventfs_create_dir+0x7a/0x590\n   event_create_dir+0x2fb/0xcf0\n   trace_add_event_call+0xbf/0x150\n  [...]\n  Freed by task 11:\n   kfree+0x1db/0x5b0\n   srcu_invoke_callbacks+0x3a3/0x620\n   process_one_work+0x937/0x1810\n   worker_thread+0x4f1/0xd60\n\nBefore commit 8e556432477e (\"eventfs: Use SRCU for freeing\neventfs_inodes\") release_ei() used call_rcu(), which covered the walker,\nwhile eventfs_iterate() needs the SRCU grace period. Wait for both and\nchain call_rcu() from the SRCU callback."}],"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"},"scenarios":[{"lang":"en","value":"AV:L - A local newfstatat() pathwalk reaches lookup_fast()->tracefs_d_revalidate(); concurrent invalidation invokes tracefs_d_release()->eventfs_d_release()->put_ei()->release_ei(), the patched free path. No network or device input reaches this tracefs race.\nAC:L - The attacker can create a nonpersistent user event, instantiate its dentry, then unregister and close it while concurrent threads loop newfstatat(). This controls event teardown, dentry invalidation, and the RCU walk, making the race repeatable.\nPR:L - user_event_capable() requires CAP_PERFMON only for USER_EVENT_REG_PERSIST; ordinary DIAG_IOCSREG and DIAG_IOCSUNREG have no capable() check. A low-privilege user with delegated DAC access to user_events_data can create and auto-delete the required eventfs directory.\nUI:N - The same process registers the event, stats events/user_events/<name>, and unregisters or closes it to trigger auto-deletion; no victim action is required.\nS:U - The dangling d_fsdata access in tracefs_d_revalidate() and the release_ei() free both occur within the host kernel. Resulting privilege escalation does not cross a VM, IOMMU, or other security authority.\nC:H - After free_ei_rcu() frees the eventfs_inode, dentry->d_fsdata remains a dangling pointer read by tracefs_d_revalidate(). Repeated event creation permits slab grooming and attacker-influenced reuse, giving the disclosure potential of a kernel UAF.\nI:H - release_ei() permits an RCU walker to retain a pointer into a freed kmalloc object that the attacker can churn through eventfs_create_dir(). Reclaiming the object provides the heap-spraying and control-flow corruption potential of an exploitable kernel UAF.\nA:H - The reported KASAN trace demonstrates a slab-use-after-free read in tracefs_d_revalidate() after free_ei_rcu() calls kfree(). Repeatedly racing event deletion with pathwalk can therefore cause a kernel oops or panic."}]}],"providerMetadata":{"dateUpdated":"2026-10-31T12:44:40.199Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/5819018dc29fb2ac2fd4865d507f9893c89c0624"},{"url":"https://git.kernel.org/stable/c/dd2c767814a876be0f16f0b7f98a403dc176f51e"},{"url":"https://git.kernel.org/stable/c/4586ef24ce390e8becb9f3e5852d5d3978b01c33"},{"url":"https://git.kernel.org/stable/c/45fcfd5d9c10e0aa977ed5b9bd445707e01bb107"},{"url":"https://git.kernel.org/stable/c/2cd88c498ecff8e22bf4c397b8eb226db70ac343"}],"title":"eventfs: Free the eventfs_inode after an rcu grace period too","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99173","datePublished":"2026-10-28T10:35:28.017Z","dateReserved":"2026-09-25T10:25:14.399Z","dateUpdated":"2026-10-31T12:44:40.199Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-28 11:17:37","lastModifiedDate":"2026-10-31 13:17:58","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":"99173","Ordinal":"1","Title":"eventfs: Free the eventfs_inode after an rcu grace period too","CVE":"CVE-2026-99173","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99173","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\neventfs: Free the eventfs_inode after an rcu grace period too\n\ntracefs_d_revalidate() reads ->is_freed of the eventfs_inode that\ndentry->d_fsdata points to, and ->d_revalidate() is called in rcu\npathwalk mode with nothing but rcu_read_lock() held. The dentry itself\nstays around for such a walker, but tracefs_d_release() drops its\nreference to the eventfs_inode when the dentry is killed, and\nrelease_ei() then frees it after a grace period of eventfs_srcu. An\nSRCU grace period doesn't wait for rcu_read_lock() sections, so the\nwalker can read an eventfs_inode that is already gone.\n\nWith a pathwalk held up in tracefs_d_revalidate() while the dentry goes\naway:\n\n  BUG: KASAN: slab-use-after-free in tracefs_d_revalidate+0x76/0x90\n  Read of size 1 at addr ff1100010152d8d0 by task walker/97\n  Call Trace:\n   <TASK>\n   tracefs_d_revalidate+0x76/0x90\n   lookup_fast+0x320/0x640\n   path_lookupat+0x160/0xb00\n   filename_lookup+0x1f1/0x5b0\n   vfs_statx+0xd7/0x3b0\n   vfs_fstatat+0x4d/0x90\n   __do_sys_newfstatat+0xa0/0x100\n   do_syscall_64+0x10e/0x5e0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  [...]\n  Allocated by task 1:\n   __kmalloc_cache_noprof+0x249/0x560\n   eventfs_create_dir+0x7a/0x590\n   event_create_dir+0x2fb/0xcf0\n   trace_add_event_call+0xbf/0x150\n  [...]\n  Freed by task 11:\n   kfree+0x1db/0x5b0\n   srcu_invoke_callbacks+0x3a3/0x620\n   process_one_work+0x937/0x1810\n   worker_thread+0x4f1/0xd60\n\nBefore commit 8e556432477e (\"eventfs: Use SRCU for freeing\neventfs_inodes\") release_ei() used call_rcu(), which covered the walker,\nwhile eventfs_iterate() needs the SRCU grace period. Wait for both and\nchain call_rcu() from the SRCU callback.","Type":"Description","Title":"eventfs: Free the eventfs_inode after an rcu grace period too"}]}}}