{"id":"CVE-2026-98840","state":"PUBLISHED","title":"vc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF\n\nThe reload of 'vc' added by commit 8fb9ea65c9d1 (\"vc_screen: reload load\nof struct vc_data pointer in vcs_write() to avoid UAF\") sits after the\n'if (ret)' block, so the copy-failure break path exits the loop without\nreloading vc. If the vc was kfree()'d via vc_port_destruct during the\nunlocked copy_from_user() window, the post-loop\n'if (written && vc) vcs_scr_updated(vc)' is reached with a stale\nnon-NULL vc. The '&& vc' guard from commit a287620312dc (\"vc_screen:\nfix null-ptr-deref in vcs_notifier() during concurrent vcs_write\") only\nhandles the NULL case, not this stale-non-NULL case; vcs_notifier() then\nreads param->vc->vc_num from freed memory:\n\n  BUG: KASAN: slab-use-after-free in vcs_notifier+0x7c/0xd0\n  Read of size 2 at addr ffff888007149190\n  Call Trace:\n   vcs_notifier+0x7c/0xd0\n   atomic_notifier_call_chain+0x70/0xa0\n   vcs_scr_updated+0x77/0xa0\n   vcs_write+0x71b/0x7e0\n  Allocated by task: vc_allocate -> con_install -> tty_open\n  Freed by task: kfree <- vt_ioctl (VT_DISALLOCATE -> vc_port_destruct)\n\nMove the reload to immediately after console_lock(), before 'if (ret)',\nso every break path below passes a fresh vc to the post-loop\nvcs_scr_updated().","publishedAt":"2026-10-18T15:50:14.029Z","updatedAt":"2026-10-30T12:40:08.759Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"43a6281790273c1b0a9ab76609ff0245b968f1e6","status":"affected","lessThan":"cbc05413d3694193494b2374b56bae801ac41fec","versionType":"git"},{"version":"b6bbb85cf45bf0b070e741997fe0af3a772c5ad5","status":"affected","lessThan":"942742000a0288d4ca60c448894aabacd48004d5","versionType":"git"},{"version":"ff4806202749a51938236214adc0281481a57366","status":"affected","lessThan":"c9f56d4b29792a62b17f2051ba93fd3b40a479ec","versionType":"git"},{"version":"8232fca738011ca2ec865b46ec721d1796dc0580","status":"affected","lessThan":"c073d01f6f5367c3a4f07efd507274ed0d03acd0","versionType":"git"},{"version":"73049768ad57145acd337102c5aa3c788e6642c8","status":"affected","lessThan":"1485a3dd97ab1af2605243cabe6b604546d46dd1","versionType":"git"},{"version":"7cc3dd79777f6ae4625ec37e84dd18a26dc88bde","status":"affected","lessThan":"233a2e190b12884d186027d0b86d43a48799b69c","versionType":"git"},{"version":"a287620312dc6dcb9a093417a0e589bf30fcf38a","status":"affected","lessThan":"9dfcadc5e003fb250dd471db90144bd5366140e9","versionType":"git"},{"version":"a287620312dc6dcb9a093417a0e589bf30fcf38a","status":"affected","lessThan":"226bd5603371cd9f6642cbb9e9a677f445de3530","versionType":"git"},{"version":"74be188eb2dc1c99d63986167b9a67d415fe7326","status":"affected","versionType":"git"},{"version":"09a43e81279b8da15526da09877134b8bcf618b0","status":"affected","versionType":"git"},{"version":"5.10.260","status":"affected","lessThan":"5.10.273","versionType":"semver"},{"version":"5.15.211","status":"affected","lessThan":"5.15.224","versionType":"semver"},{"version":"6.1.177","status":"affected","lessThan":"6.1.191","versionType":"semver"},{"version":"6.6.144","status":"affected","lessThan":"6.6.160","versionType":"semver"},{"version":"6.12.95","status":"affected","lessThan":"6.12.113","versionType":"semver"},{"version":"6.18.37","status":"affected","lessThan":"6.18.56","versionType":"semver"},{"version":"7.0.14","status":"affected","lessThan":"7.1","versionType":"semver"},{"version":"7.1.2","status":"affected","lessThan":"7.2","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/tty/vt/vc_screen.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.2","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.56","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.10","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/tty/vt/vc_screen.c"]}],"references":["https://git.kernel.org/stable/c/cbc05413d3694193494b2374b56bae801ac41fec","https://git.kernel.org/stable/c/942742000a0288d4ca60c448894aabacd48004d5","https://git.kernel.org/stable/c/c9f56d4b29792a62b17f2051ba93fd3b40a479ec","https://git.kernel.org/stable/c/c073d01f6f5367c3a4f07efd507274ed0d03acd0","https://git.kernel.org/stable/c/1485a3dd97ab1af2605243cabe6b604546d46dd1","https://git.kernel.org/stable/c/233a2e190b12884d186027d0b86d43a48799b69c","https://git.kernel.org/stable/c/9dfcadc5e003fb250dd471db90144bd5366140e9","https://git.kernel.org/stable/c/226bd5603371cd9f6642cbb9e9a677f445de3530"],"weaknesses":[],"ingestedAt":"2026-10-30T13:00:06.648Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98840.json","commit":"cb14bf1b43b0c9f05f7f40eae2246263fd430780","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98840","state":"PUBLISHED","datePublished":"2026-10-18T15:50:14.029Z","dateUpdated":"2026-10-30T12:40:08.759Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.373Z"},"containers":{"cna":{"title":"vc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nvc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF\n\nThe reload of 'vc' added by commit 8fb9ea65c9d1 (\"vc_screen: reload load\nof struct vc_data pointer in vcs_write() to avoid UAF\") sits after the\n'if (ret)' block, so the copy-failure break path exits the loop without\nreloading vc. If the vc was kfree()'d via vc_port_destruct during the\nunlocked copy_from_user() window, the post-loop\n'if (written && vc) vcs_scr_updated(vc)' is reached with a stale\nnon-NULL vc. The '&& vc' guard from commit a287620312dc (\"vc_screen:\nfix null-ptr-deref in vcs_notifier() during concurrent vcs_write\") only\nhandles the NULL case, not this stale-non-NULL case; vcs_notifier() then\nreads param->vc->vc_num from freed memory:\n\n  BUG: KASAN: slab-use-after-free in vcs_notifier+0x7c/0xd0\n  Read of size 2 at addr ffff888007149190\n  Call Trace:\n   vcs_notifier+0x7c/0xd0\n   atomic_notifier_call_chain+0x70/0xa0\n   vcs_scr_updated+0x77/0xa0\n   vcs_write+0x71b/0x7e0\n  Allocated by task: vc_allocate -> con_install -> tty_open\n  Freed by task: kfree <- vt_ioctl (VT_DISALLOCATE -> vc_port_destruct)\n\nMove the reload to immediately after console_lock(), before 'if (ret)',\nso every break path below passes a fresh vc to the post-loop\nvcs_scr_updated()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"43a6281790273c1b0a9ab76609ff0245b968f1e6","status":"affected","lessThan":"cbc05413d3694193494b2374b56bae801ac41fec","versionType":"git"},{"version":"b6bbb85cf45bf0b070e741997fe0af3a772c5ad5","status":"affected","lessThan":"942742000a0288d4ca60c448894aabacd48004d5","versionType":"git"},{"version":"ff4806202749a51938236214adc0281481a57366","status":"affected","lessThan":"c9f56d4b29792a62b17f2051ba93fd3b40a479ec","versionType":"git"},{"version":"8232fca738011ca2ec865b46ec721d1796dc0580","status":"affected","lessThan":"c073d01f6f5367c3a4f07efd507274ed0d03acd0","versionType":"git"},{"version":"73049768ad57145acd337102c5aa3c788e6642c8","status":"affected","lessThan":"1485a3dd97ab1af2605243cabe6b604546d46dd1","versionType":"git"},{"version":"7cc3dd79777f6ae4625ec37e84dd18a26dc88bde","status":"affected","lessThan":"233a2e190b12884d186027d0b86d43a48799b69c","versionType":"git"},{"version":"a287620312dc6dcb9a093417a0e589bf30fcf38a","status":"affected","lessThan":"9dfcadc5e003fb250dd471db90144bd5366140e9","versionType":"git"},{"version":"a287620312dc6dcb9a093417a0e589bf30fcf38a","status":"affected","lessThan":"226bd5603371cd9f6642cbb9e9a677f445de3530","versionType":"git"},{"version":"74be188eb2dc1c99d63986167b9a67d415fe7326","status":"affected","versionType":"git"},{"version":"09a43e81279b8da15526da09877134b8bcf618b0","status":"affected","versionType":"git"},{"version":"5.10.260","status":"affected","lessThan":"5.10.273","versionType":"semver"},{"version":"5.15.211","status":"affected","lessThan":"5.15.224","versionType":"semver"},{"version":"6.1.177","status":"affected","lessThan":"6.1.191","versionType":"semver"},{"version":"6.6.144","status":"affected","lessThan":"6.6.160","versionType":"semver"},{"version":"6.12.95","status":"affected","lessThan":"6.12.113","versionType":"semver"},{"version":"6.18.37","status":"affected","lessThan":"6.18.56","versionType":"semver"},{"version":"7.0.14","status":"affected","lessThan":"7.1","versionType":"semver"},{"version":"7.1.2","status":"affected","lessThan":"7.2","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/tty/vt/vc_screen.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.2","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.56","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.10","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/tty/vt/vc_screen.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/cbc05413d3694193494b2374b56bae801ac41fec"},{"url":"https://git.kernel.org/stable/c/942742000a0288d4ca60c448894aabacd48004d5"},{"url":"https://git.kernel.org/stable/c/c9f56d4b29792a62b17f2051ba93fd3b40a479ec"},{"url":"https://git.kernel.org/stable/c/c073d01f6f5367c3a4f07efd507274ed0d03acd0"},{"url":"https://git.kernel.org/stable/c/1485a3dd97ab1af2605243cabe6b604546d46dd1"},{"url":"https://git.kernel.org/stable/c/233a2e190b12884d186027d0b86d43a48799b69c"},{"url":"https://git.kernel.org/stable/c/9dfcadc5e003fb250dd471db90144bd5366140e9"},{"url":"https://git.kernel.org/stable/c/226bd5603371cd9f6642cbb9e9a677f445de3530"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:40:08.759Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.260","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.211","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.177","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.144","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.95","versionEndExcluding":"6.12.113"},{"vulnerable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