{"id":"CVE-2026-89585","state":"PUBLISHED","title":"auxdisplay: charlcd: cancel backlight work on registration failure","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nauxdisplay: charlcd: cancel backlight work on registration failure\n\nWith CONFIG_CHARLCD_BL_FLASH, charlcd_init() schedules bl_work before\ncharlcd_register() calls misc_register(). If registration fails, the\ncaller frees the charlcd object while delayed work still contains its\naddress.\n\nAdd charlcd_deinit() to cancel the delayed work and turn the backlight\noff. Use it for both registration rollback and normal unregistration.","publishedAt":"2026-09-11T19:44:50.592Z","updatedAt":"2026-10-19T08:49:17.989Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"cd97b3c68fe3c06c8067cc59d7dff976c5b7ea04","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"22586432c1aba89d9bd33f3173408dac830f220b","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"6eaed64a32e550daf0dc9549742b3ab9e41d984f","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"fe7ba73dde94c5f413b1588cd444b49105015dda","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"84858671842ae5857b9ed1202b62f9045373dcd1","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"ff2fb3c1e60cb247ea3e28c0ea0bea81c18f7755","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"e3e3bf40916c1e810df03958cfa7ba6883cdce79","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/auxdisplay/charlcd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.12","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/auxdisplay/charlcd.c"]}],"references":["https://git.kernel.org/stable/c/cd97b3c68fe3c06c8067cc59d7dff976c5b7ea04","https://git.kernel.org/stable/c/22586432c1aba89d9bd33f3173408dac830f220b","https://git.kernel.org/stable/c/6eaed64a32e550daf0dc9549742b3ab9e41d984f","https://git.kernel.org/stable/c/fe7ba73dde94c5f413b1588cd444b49105015dda","https://git.kernel.org/stable/c/84858671842ae5857b9ed1202b62f9045373dcd1","https://git.kernel.org/stable/c/ff2fb3c1e60cb247ea3e28c0ea0bea81c18f7755","https://git.kernel.org/stable/c/e3e3bf40916c1e810df03958cfa7ba6883cdce79"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89585.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89585","state":"PUBLISHED","datePublished":"2026-09-11T19:44:50.592Z","dateUpdated":"2026-10-19T08:49:17.989Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.729Z"},"containers":{"cna":{"title":"auxdisplay: charlcd: cancel backlight work on registration failure","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nauxdisplay: charlcd: cancel backlight work on registration failure\n\nWith CONFIG_CHARLCD_BL_FLASH, charlcd_init() schedules bl_work before\ncharlcd_register() calls misc_register(). If registration fails, the\ncaller frees the charlcd object while delayed work still contains its\naddress.\n\nAdd charlcd_deinit() to cancel the delayed work and turn the backlight\noff. Use it for both registration rollback and normal unregistration."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"cd97b3c68fe3c06c8067cc59d7dff976c5b7ea04","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"22586432c1aba89d9bd33f3173408dac830f220b","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"6eaed64a32e550daf0dc9549742b3ab9e41d984f","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"fe7ba73dde94c5f413b1588cd444b49105015dda","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"84858671842ae5857b9ed1202b62f9045373dcd1","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"ff2fb3c1e60cb247ea3e28c0ea0bea81c18f7755","versionType":"git"},{"version":"39f8ea46724efbed3ca021863a22337c31be264c","status":"affected","lessThan":"e3e3bf40916c1e810df03958cfa7ba6883cdce79","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/auxdisplay/charlcd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.12","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/auxdisplay/charlcd.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/cd97b3c68fe3c06c8067cc59d7dff976c5b7ea04"},{"url":"https://git.kernel.org/stable/c/22586432c1aba89d9bd33f3173408dac830f220b"},{"url":"https://git.kernel.org/stable/c/6eaed64a32e550daf0dc9549742b3ab9e41d984f"},{"url":"https://git.kernel.org/stable/c/fe7ba73dde94c5f413b1588cd444b49105015dda"},{"url":"https://git.kernel.org/stable/c/84858671842ae5857b9ed1202b62f9045373dcd1"},{"url":"https://git.kernel.org/stable/c/ff2fb3c1e60cb247ea3e28c0ea0bea81c18f7755"},{"url":"https://git.kernel.org/stable/c/e3e3bf40916c1e810df03958cfa7ba6883cdce79"}],"metrics":[{"cvssV3_1":{"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"},"scenarios":[{"lang":"en","value":"AV:L - charlcd_register() is reached only from local auxdisplay probe (hd44780 platform, lcd2s I2C, panel parport) on character LCDs in embedded, industrial, and appliance systems; there is no network or USB-host packet path into this misc-registration error path.\nAC:L - CONFIG_CHARLCD_BL_FLASH is the default, so charlcd_init() always queues bl_work (L* poke, 4s) before misc_register(); a second charlcd consumer or LCD_MINOR 156 collision makes registration fail deterministically, then the work runs on the freed object with no attacker-uncontrollable race.\nPR:L - On multi-display or mixed hd44780/lcd2s/panel systems the second probe runs automatically at boot without init-namespace root, and an unprivileged local user can spray the heap in the 4s window; embedded/kiosk sysfs bind is also not strictly root-only. Uncertain vs High, so Low.\nUI:N - The UAF is armed during driver probe and consumed by the kernel workqueue; no victim needs to open /dev/lcd, mount a filesystem, or take any other interactive action.\nS:U - The delayed-work UAF corrupts in-kernel charlcd_priv/work_struct heap state and can escalate only within the host kernel; it does not cross a VM, IOMMU, or sandbox boundary.\nC:H - charlcd_bl_off() does container_of() on the freed delayed_work and reads priv fields, including lcd.ops, from reclaimable slab, giving a use-after-free kernel read primitive.\nI:H - The same callback invokes priv->lcd.ops->backlight on the freed object, so reclaiming the slab with a forged ops table yields a kernel function-pointer call, arbitrary write, and control-flow hijack.\nA:H - Running delayed work after charlcd_free() oopses or panics via mutex_lock on freed bl_tempo_lock or a wild ops pointer, even when the UAF is not fully exploited."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:49:17.989Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}