{"api_version":"1","generated_at":"2026-10-06T10:21:34+00:00","cve":"CVE-2026-98258","urls":{"html":"https://cve.report/CVE-2026-98258","api":"https://cve.report/api/cve/CVE-2026-98258.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98258","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98258"},"summary":{"title":"posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nposix-cpu-timers: Prevent freeing a timer which is queued on the expiry list\n\nKijo analyzed another race in the POSIX CPU timer code:\n\nCommit bf635681c906 converted cpu_timer::firing from a tristate value to a\nboolean. This lost the distinction between \"not owned by the firing list\"\nand \"still owned, but delivery was canceled\". The resulting race is:\n\n    expiry handler              timer_settime()        timer_delete()\n    --------------              ---------------        --------------\n    collect timer onto\n    private firing list\n    firing = true\n                                observes firing = true\n                                firing = false\n                                return TIMER_RETRY\n                                wait for handler\n                                                       observes firing = false\n                                                       finish deletion\n                                                       unhash and free timer\n    resume list traversal\n    read freed elist.next\n    -> UAF\n\nThe firing bit is clearly the wrong indicator since that commit.\n\nCheck whether the timer is queued on the expiry list or not instead. If it\nis queued clear the firing bit to prevent signal delivery as before and\nreturn TIMER_RETRY so the caller unlocks the timer which allows the expiry\ncode to make progress and remove it from the list.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-06 09:18:14","updated_at":"2026-10-06 09:18:14"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd","name":"https://git.kernel.org/stable/c/c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4336e3f47d9d516441066e9a65eaf076790d8d45","name":"https://git.kernel.org/stable/c/4336e3f47d9d516441066e9a65eaf076790d8d45","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9971dac1a77845ff467146915fcbb9170f6a8209","name":"https://git.kernel.org/stable/c/9971dac1a77845ff467146915fcbb9170f6a8209","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98258","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98258","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bf635681c906ad056d1fda325de8d1c12c9f8201 9971dac1a77845ff467146915fcbb9170f6a8209 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bf635681c906ad056d1fda325de8d1c12c9f8201 4336e3f47d9d516441066e9a65eaf076790d8d45 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bf635681c906ad056d1fda325de8d1c12c9f8201 c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.13","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.13 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.54 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.8 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc4 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["kernel/time/posix-cpu-timers.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"9971dac1a77845ff467146915fcbb9170f6a8209","status":"affected","version":"bf635681c906ad056d1fda325de8d1c12c9f8201","versionType":"git"},{"lessThan":"4336e3f47d9d516441066e9a65eaf076790d8d45","status":"affected","version":"bf635681c906ad056d1fda325de8d1c12c9f8201","versionType":"git"},{"lessThan":"c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd","status":"affected","version":"bf635681c906ad056d1fda325de8d1c12c9f8201","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["kernel/time/posix-cpu-timers.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.13"},{"lessThan":"6.13","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.54","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.8","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc4","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.54","versionStartIncluding":"6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.8","versionStartIncluding":"6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc4","versionStartIncluding":"6.13","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nposix-cpu-timers: Prevent freeing a timer which is queued on the expiry list\n\nKijo analyzed another race in the POSIX CPU timer code:\n\nCommit bf635681c906 converted cpu_timer::firing from a tristate value to a\nboolean. This lost the distinction between \"not owned by the firing list\"\nand \"still owned, but delivery was canceled\". The resulting race is:\n\n    expiry handler              timer_settime()        timer_delete()\n    --------------              ---------------        --------------\n    collect timer onto\n    private firing list\n    firing = true\n                                observes firing = true\n                                firing = false\n                                return TIMER_RETRY\n                                wait for handler\n                                                       observes firing = false\n                                                       finish deletion\n                                                       unhash and free timer\n    resume list traversal\n    read freed elist.next\n    -> UAF\n\nThe firing bit is clearly the wrong indicator since that commit.\n\nCheck whether the timer is queued on the expiry list or not instead. If it\nis queued clear the firing bit to prevent signal delivery as before and\nreturn TIMER_RETRY so the caller unlocks the timer which allows the expiry\ncode to make progress and remove it from the list."}],"providerMetadata":{"dateUpdated":"2026-10-06T08:45:23.379Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/9971dac1a77845ff467146915fcbb9170f6a8209"},{"url":"https://git.kernel.org/stable/c/4336e3f47d9d516441066e9a65eaf076790d8d45"},{"url":"https://git.kernel.org/stable/c/c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd"}],"title":"posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98258","datePublished":"2026-10-06T08:45:23.379Z","dateReserved":"2026-09-25T10:25:14.332Z","dateUpdated":"2026-10-06T08:45:23.379Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-06 09:18:14","lastModifiedDate":"2026-10-06 09:18:14","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98258","Ordinal":"1","Title":"posix-cpu-timers: Prevent freeing a timer which is queued on the","CVE":"CVE-2026-98258","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98258","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nposix-cpu-timers: Prevent freeing a timer which is queued on the expiry list\n\nKijo analyzed another race in the POSIX CPU timer code:\n\nCommit bf635681c906 converted cpu_timer::firing from a tristate value to a\nboolean. This lost the distinction between \"not owned by the firing list\"\nand \"still owned, but delivery was canceled\". The resulting race is:\n\n    expiry handler              timer_settime()        timer_delete()\n    --------------              ---------------        --------------\n    collect timer onto\n    private firing list\n    firing = true\n                                observes firing = true\n                                firing = false\n                                return TIMER_RETRY\n                                wait for handler\n                                                       observes firing = false\n                                                       finish deletion\n                                                       unhash and free timer\n    resume list traversal\n    read freed elist.next\n    -> UAF\n\nThe firing bit is clearly the wrong indicator since that commit.\n\nCheck whether the timer is queued on the expiry list or not instead. If it\nis queued clear the firing bit to prevent signal delivery as before and\nreturn TIMER_RETRY so the caller unlocks the timer which allows the expiry\ncode to make progress and remove it from the list.","Type":"Description","Title":"posix-cpu-timers: Prevent freeing a timer which is queued on the"}]}}}