{"api_version":"1","generated_at":"2026-09-21T20:31:16+00:00","cve":"CVE-2026-90260","urls":{"html":"https://cve.report/CVE-2026-90260","api":"https://cve.report/api/cve/CVE-2026-90260.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-90260","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90260"},"summary":{"title":"btrfs: zoned: don't clobber the extent buffer when zeroing it out","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: zoned: don't clobber the extent buffer when zeroing it out\n\nOn a zoned filesystem a freed-but-still-dirty tree block is written out\nas zeros (EXTENT_BUFFER_ZONED_ZEROOUT) only to keep the zone write\npointer advancing. btree_csum_one_bio() implemented this by memzeroing\nthe extent buffer's own folios before submission.\n\nThat destroys the in-memory buffer while it may still be referenced. In\nparticular btrfs_free_tree_block() can run on it afterwards and reads\nthe header to add a delayed reference; once the header has been zeroed\nit frees bytenr 0 and corrupts the extent tree (the\nbtrfs_header_bytenr(buf) != 0 ASSERT in btrfs_free_tree_block(), or an\n\"unable to find ref\" abort). It is flaky and reproduces under fsstress,\ne.g. generic/461 and generic/013.\n\nWrite the zeros to disk from the shared zero page instead and leave the\nextent buffer content untouched, so any later reference - including the\ndelayed reference from btrfs_free_tree_block() - still sees a valid\nheader. end_bbio_meta_write() now clears writeback on the buffer's own\nfolios, as the bio no longer carries them.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:17:22","updated_at":"2026-09-18 18:17:51"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.1","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","baseScore":7.1,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.1","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","data":{"baseScore":7.1,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/98e3747587f9f87f010d8d7e55786216249a94af","name":"https://git.kernel.org/stable/c/98e3747587f9f87f010d8d7e55786216249a94af","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/92484ad014f2e2b0e0e7bbc1610951e978cf557c","name":"https://git.kernel.org/stable/c/92484ad014f2e2b0e0e7bbc1610951e978cf557c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/db4b9eefc8ee0bcaeee4d5e6a7313905f6a2fe7c","name":"https://git.kernel.org/stable/c/db4b9eefc8ee0bcaeee4d5e6a7313905f6a2fe7c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90260","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90260","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected aa6313e6ff2bfbf736a2739047bba355d8241584 92484ad014f2e2b0e0e7bbc1610951e978cf557c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected aa6313e6ff2bfbf736a2739047bba355d8241584 98e3747587f9f87f010d8d7e55786216249a94af git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected aa6313e6ff2bfbf736a2739047bba355d8241584 db4b9eefc8ee0bcaeee4d5e6a7313905f6a2fe7c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.8","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.8 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.52 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"90260","cve":"CVE-2026-90260","epss":"0.001570000","percentile":"0.053280000","score_date":"2026-09-20","updated_at":"2026-09-21 00:10:09"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/btrfs/disk-io.c","fs/btrfs/extent_io.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"92484ad014f2e2b0e0e7bbc1610951e978cf557c","status":"affected","version":"aa6313e6ff2bfbf736a2739047bba355d8241584","versionType":"git"},{"lessThan":"98e3747587f9f87f010d8d7e55786216249a94af","status":"affected","version":"aa6313e6ff2bfbf736a2739047bba355d8241584","versionType":"git"},{"lessThan":"db4b9eefc8ee0bcaeee4d5e6a7313905f6a2fe7c","status":"affected","version":"aa6313e6ff2bfbf736a2739047bba355d8241584","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/btrfs/disk-io.c","fs/btrfs/extent_io.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.8"},{"lessThan":"6.8","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.52","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.52","versionStartIncluding":"6.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"6.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.8","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: zoned: don't clobber the extent buffer when zeroing it out\n\nOn a zoned filesystem a freed-but-still-dirty tree block is written out\nas zeros (EXTENT_BUFFER_ZONED_ZEROOUT) only to keep the zone write\npointer advancing. btree_csum_one_bio() implemented this by memzeroing\nthe extent buffer's own folios before submission.\n\nThat destroys the in-memory buffer while it may still be referenced. In\nparticular btrfs_free_tree_block() can run on it afterwards and reads\nthe header to add a delayed reference; once the header has been zeroed\nit frees bytenr 0 and corrupts the extent tree (the\nbtrfs_header_bytenr(buf) != 0 ASSERT in btrfs_free_tree_block(), or an\n\"unable to find ref\" abort). It is flaky and reproduces under fsstress,\ne.g. generic/461 and generic/013.\n\nWrite the zeros to disk from the shared zero page instead and leave the\nextent buffer content untouched, so any later reference - including the\ndelayed reference from btrfs_free_tree_block() - still sees a valid\nheader. end_bbio_meta_write() now clears writeback on the buffer's own\nfolios, as the bio no longer carries them."}],"metrics":[{"cvssV3_1":{"baseScore":7.1,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The trigger is local VFS syscalls on a mounted zoned btrfs: unlink → btrfs_unlink() → btrfs_del_items() → btrfs_clear_buffer_dirty() sets EXTENT_BUFFER_ZONED_ZEROOUT, then fsync → btrfs_sync_file() → btree_writepages() → write_one_eb() → btree_csum_one_bio(). No network protocol carries the data that causes the clobber.\nAC:L - The attacker drives both sides: unlink/write churn that sets ZONED_ZEROOUT in btrfs_clear_buffer_dirty() while leaving DIRTY set, and fsync or btrfs_btree_balance_dirty() running btree_writepages(). lock_extent_buffer_for_io() drops the tree lock before the memzero, and btrfs_del_leaf() unlocks before btrfs_free_tree_block() reads the header.\nPR:L - btrfs_unlink() and btrfs_sync_file() have no capability check; an unprivileged user with write access on the already-mounted zoned volume can COW-free tree blocks and kick metadata writeback (fsync or the btrfs_btree_balance_dirty() at the end of btrfs_unlink()).\nUI:N - The attacker performs the unlink/write/fsync sequence themselves on files they can write; this is a runtime COW/writeback race on a legitimate zoned btrfs (reproduced by fsstress generic/461 and generic/013), not a crafted image a victim must mount.\nS:U - The clobbered extent-buffer folios and the bad delayed refs stay inside this mount's btrfs metadata in the host kernel; there is no KVM/Xen guest-to-host, IOMMU, or sandbox boundary crossing.\nC:N - btree_csum_one_bio() calls memzero_extent_buffer(eb, 0, eb->len), which memset_extent_buffer() restricts to that buffer's own folios via check_eb_range(); the overwrite is zeros, not an out-of-bounds read or kernel-pointer leak.\nI:H - After the header is zeroed, btrfs_free_tree_block() queues a BTRFS_DROP_DELAYED_REF with owning_root=btrfs_header_owner(buf)==0 and level=btrfs_header_level(buf)==0, so __btrfs_free_extent() applies a mismatched backref to the shared extent tree and corrupts metadata for every file on the volume.\nA:H - The mismatched delayed ref hits abort_and_dump() → btrfs_abort_transaction(-EUCLEAN) → __btrfs_handle_fs_error() → btrfs_set_sb_rdonly(), forcing the whole filesystem read-only; with CONFIG_BTRFS_ASSERT, ASSERT(btrfs_header_bytenr(buf) != 0) in btrfs_free_tree_block() panics."}]}],"providerMetadata":{"dateUpdated":"2026-09-18T17:54:13.818Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/92484ad014f2e2b0e0e7bbc1610951e978cf557c"},{"url":"https://git.kernel.org/stable/c/98e3747587f9f87f010d8d7e55786216249a94af"},{"url":"https://git.kernel.org/stable/c/db4b9eefc8ee0bcaeee4d5e6a7313905f6a2fe7c"}],"title":"btrfs: zoned: don't clobber the extent buffer when zeroing it out","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-90260","datePublished":"2026-09-17T16:07:58.102Z","dateReserved":"2026-09-11T19:38:34.796Z","dateUpdated":"2026-09-18T17:54:13.818Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:17:22","lastModifiedDate":"2026-09-18 18:17:51","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:N/I:H/A:H","baseScore":7.1,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.2}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"90260","Ordinal":"1","Title":"btrfs: zoned: don't clobber the extent buffer when zeroing it ou","CVE":"CVE-2026-90260","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"90260","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: zoned: don't clobber the extent buffer when zeroing it out\n\nOn a zoned filesystem a freed-but-still-dirty tree block is written out\nas zeros (EXTENT_BUFFER_ZONED_ZEROOUT) only to keep the zone write\npointer advancing. btree_csum_one_bio() implemented this by memzeroing\nthe extent buffer's own folios before submission.\n\nThat destroys the in-memory buffer while it may still be referenced. In\nparticular btrfs_free_tree_block() can run on it afterwards and reads\nthe header to add a delayed reference; once the header has been zeroed\nit frees bytenr 0 and corrupts the extent tree (the\nbtrfs_header_bytenr(buf) != 0 ASSERT in btrfs_free_tree_block(), or an\n\"unable to find ref\" abort). It is flaky and reproduces under fsstress,\ne.g. generic/461 and generic/013.\n\nWrite the zeros to disk from the shared zero page instead and leave the\nextent buffer content untouched, so any later reference - including the\ndelayed reference from btrfs_free_tree_block() - still sees a valid\nheader. end_bbio_meta_write() now clears writeback on the buffer's own\nfolios, as the bio no longer carries them.","Type":"Description","Title":"btrfs: zoned: don't clobber the extent buffer when zeroing it ou"}]}}}