{"api_version":"1","generated_at":"2026-11-01T09:41:05+00:00","cve":"CVE-2026-99156","urls":{"html":"https://cve.report/CVE-2026-99156","api":"https://cve.report/api/cve/CVE-2026-99156.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99156","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99156"},"summary":{"title":"scsi: st: Fix use-after-free race between st_remove() and st_open()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: st: Fix use-after-free race between st_remove() and st_open()\n\nst_remove() drops the probe reference on the scsi_tape with kref_put()\nand only afterwards removes its index from st_index_idr. If that was the\nlast reference, scsi_tape_release() frees the structure while it is\nstill published in the idr.\n\nscsi_tape_get(), called from st_open(), looks up the tape in\nst_index_idr and takes a reference under st_ref_mutex and\nst_index_lock. remove_cdevs() does not wait for opens that are already\npast chrdev_open(), so an open that is blocked on st_ref_mutex while\nst_remove() holds it can take the mutex as soon as st_remove() drops it,\nfind the freed tpnt in the idr and call kref_get() on it:\n\n  BUG: KASAN: slab-use-after-free in st_open\n  Write of size 4 ...\n   st_open (drivers/scsi/st.c:254 drivers/scsi/st.c:1291)\n   chrdev_open\n  ...\n  Freed by task ...:\n   kfree\n   st_remove (drivers/scsi/st.c:4512)\n\nRemove the index from the idr before dropping the reference, all under\nst_ref_mutex. A concurrent scsi_tape_get() now either runs first and\nholds a valid reference that keeps the tape alive, or runs afterwards\nand finds nothing, so st_open() fails with -ENXIO.\n\nThis restores the ordering st_remove() had before the conversion to\nst_index_idr, where the tape was unpublished from scsi_tapes[] before\nthe final kref_put().","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-28 11:17:35","updated_at":"2026-10-31 13:17:57"},"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/71caf7f84bd62a4bf91cc95abd2de690afb8d15f","name":"https://git.kernel.org/stable/c/71caf7f84bd62a4bf91cc95abd2de690afb8d15f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5ef230f734e0d23db007c8405f38b7e226740084","name":"https://git.kernel.org/stable/c/5ef230f734e0d23db007c8405f38b7e226740084","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/00ff1128123d4bdfacd28d68fb4b6e6f657a3648","name":"https://git.kernel.org/stable/c/00ff1128123d4bdfacd28d68fb4b6e6f657a3648","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7d7f9d2ee4b0841f3eba9fa3627044ad329428de","name":"https://git.kernel.org/stable/c/7d7f9d2ee4b0841f3eba9fa3627044ad329428de","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d9517fc39ec3ee13eadefdc17f45300f7d23ed8c","name":"https://git.kernel.org/stable/c/d9517fc39ec3ee13eadefdc17f45300f7d23ed8c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a1647b653549ff29f0422a63eabf329b842f3822","name":"https://git.kernel.org/stable/c/a1647b653549ff29f0422a63eabf329b842f3822","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/18a0e3733ce38718688e813e5e2d1106bd4830e5","name":"https://git.kernel.org/stable/c/18a0e3733ce38718688e813e5e2d1106bd4830e5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e7a5da4a4820210aa7d7cd8e6eb25aabe9e5b5a7","name":"https://git.kernel.org/stable/c/e7a5da4a4820210aa7d7cd8e6eb25aabe9e5b5a7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99156","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99156","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6c648d95a6af4a79241a916871df17c84c68ea20 7d7f9d2ee4b0841f3eba9fa3627044ad329428de git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6c648d95a6af4a79241a916871df17c84c68ea20 d9517fc39ec3ee13eadefdc17f45300f7d23ed8c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6c648d95a6af4a79241a916871df17c84c68ea20 e7a5da4a4820210aa7d7cd8e6eb25aabe9e5b5a7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6c648d95a6af4a79241a916871df17c84c68ea20 00ff1128123d4bdfacd28d68fb4b6e6f657a3648 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.224 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.191 6.1.* 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":"99156","cve":"CVE-2026-99156","epss":"0.001830000","percentile":"0.079280000","score_date":"2026-10-31","updated_at":"2026-11-01 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the Linux kernel, the following vulnerability has been resolved:\n\nscsi: st: Fix use-after-free race between st_remove() and st_open()\n\nst_remove() drops the probe reference on the scsi_tape with kref_put()\nand only afterwards removes its index from st_index_idr. If that was the\nlast reference, scsi_tape_release() frees the structure while it is\nstill published in the idr.\n\nscsi_tape_get(), called from st_open(), looks up the tape in\nst_index_idr and takes a reference under st_ref_mutex and\nst_index_lock. remove_cdevs() does not wait for opens that are already\npast chrdev_open(), so an open that is blocked on st_ref_mutex while\nst_remove() holds it can take the mutex as soon as st_remove() drops it,\nfind the freed tpnt in the idr and call kref_get() on it:\n\n  BUG: KASAN: slab-use-after-free in st_open\n  Write of size 4 ...\n   st_open (drivers/scsi/st.c:254 drivers/scsi/st.c:1291)\n   chrdev_open\n  ...\n  Freed by task ...:\n   kfree\n   st_remove (drivers/scsi/st.c:4512)\n\nRemove the index from the idr before dropping the reference, all under\nst_ref_mutex. A concurrent scsi_tape_get() now either runs first and\nholds a valid reference that keeps the tape alive, or runs afterwards\nand finds nothing, so st_open() fails with -ENXIO.\n\nThis restores the ordering st_remove() had before the conversion to\nst_index_idr, where the tape was unpublished from scsi_tapes[] before\nthe final kref_put()."}],"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 openat() reaches st_open() through chrdev_open(), then scsi_tape_get(); concurrent hot-unplug reaches the patched st_remove() through __scsi_remove_device(), with no network-supplied input.\nAC:L - A tape-device user controlling a hotpluggable TYPE_TAPE device can flood /dev/stN opens while disconnecting it, controlling both st_open() and st_remove() and retrying the race at will.\nPR:L - st_open() and scsi_tape_get() perform no capability check; may_open() applies device-node DAC and device-cgroup policy, so a tape-group user controlling an external tape needs no init-namespace administrative privilege.\nUI:N - The attacker performs both the /dev/stN open flood and device disconnect; no separate victim must open the tape, remove it, or mount attacker-supplied content.\nS:U - The freed scsi_tape object and subsequent corruption remain within the host kernel's SCSI-tape authority, without crossing a VM, IOMMU, or sandbox security boundary.\nC:H - st_remove() leaves a freed kmalloc-1k scsi_tape in st_index_idr; scsi_tape_get() reads its device pointer and st_open() follows buffer and mode pointers from reclaimable storage, enabling kernel-memory disclosure.\nI:H - kref_get() performs a confirmed four-byte write into the freed scsi_tape, and successful reclamation exposes further st_open() writes through in_use, state, and buffer fields, supporting control-flow hijacking.\nA:H - The stale device and buffer pointers are subsequently dereferenced by scsi_device_get() and st_open() buffer handling; the reported UAF proceeds to unrelated corruption, oops/GPF, and kernel panic."}]}],"providerMetadata":{"dateUpdated":"2026-10-31T12:44:14.895Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/7d7f9d2ee4b0841f3eba9fa3627044ad329428de"},{"url":"https://git.kernel.org/stable/c/d9517fc39ec3ee13eadefdc17f45300f7d23ed8c"},{"url":"https://git.kernel.org/stable/c/e7a5da4a4820210aa7d7cd8e6eb25aabe9e5b5a7"},{"url":"https://git.kernel.org/stable/c/00ff1128123d4bdfacd28d68fb4b6e6f657a3648"},{"url":"https://git.kernel.org/stable/c/5ef230f734e0d23db007c8405f38b7e226740084"},{"url":"https://git.kernel.org/stable/c/a1647b653549ff29f0422a63eabf329b842f3822"},{"url":"https://git.kernel.org/stable/c/18a0e3733ce38718688e813e5e2d1106bd4830e5"},{"url":"https://git.kernel.org/stable/c/71caf7f84bd62a4bf91cc95abd2de690afb8d15f"}],"title":"scsi: st: Fix use-after-free race between st_remove() and st_open()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99156","datePublished":"2026-10-28T10:35:10.493Z","dateReserved":"2026-09-25T10:25:14.397Z","dateUpdated":"2026-10-31T12:44:14.895Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-28 11:17:35","lastModifiedDate":"2026-10-31 13:17:57","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":"99156","Ordinal":"1","Title":"scsi: st: Fix use-after-free race between st_remove() and st_ope","CVE":"CVE-2026-99156","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99156","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: st: Fix use-after-free race between st_remove() and st_open()\n\nst_remove() drops the probe reference on the scsi_tape with kref_put()\nand only afterwards removes its index from st_index_idr. If that was the\nlast reference, scsi_tape_release() frees the structure while it is\nstill published in the idr.\n\nscsi_tape_get(), called from st_open(), looks up the tape in\nst_index_idr and takes a reference under st_ref_mutex and\nst_index_lock. remove_cdevs() does not wait for opens that are already\npast chrdev_open(), so an open that is blocked on st_ref_mutex while\nst_remove() holds it can take the mutex as soon as st_remove() drops it,\nfind the freed tpnt in the idr and call kref_get() on it:\n\n  BUG: KASAN: slab-use-after-free in st_open\n  Write of size 4 ...\n   st_open (drivers/scsi/st.c:254 drivers/scsi/st.c:1291)\n   chrdev_open\n  ...\n  Freed by task ...:\n   kfree\n   st_remove (drivers/scsi/st.c:4512)\n\nRemove the index from the idr before dropping the reference, all under\nst_ref_mutex. A concurrent scsi_tape_get() now either runs first and\nholds a valid reference that keeps the tape alive, or runs afterwards\nand finds nothing, so st_open() fails with -ENXIO.\n\nThis restores the ordering st_remove() had before the conversion to\nst_index_idr, where the tape was unpublished from scsi_tapes[] before\nthe final kref_put().","Type":"Description","Title":"scsi: st: Fix use-after-free race between st_remove() and st_ope"}]}}}