{"api_version":"1","generated_at":"2026-07-04T10:11:55+00:00","cve":"CVE-2026-31702","urls":{"html":"https://cve.report/CVE-2026-31702","api":"https://cve.report/api/cve/CVE-2026-31702.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31702","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31702"},"summary":{"title":"f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()\n\nIn f2fs_compress_write_end_io(), dec_page_count(sbi, type) can bring\nthe F2FS_WB_CP_DATA counter to zero, unblocking\nf2fs_wait_on_all_pages() in f2fs_put_super() on a concurrent unmount\nCPU. The unmount path then proceeds to call\nf2fs_destroy_page_array_cache(sbi), which destroys\nsbi->page_array_slab via kmem_cache_destroy(), and eventually\nkfree(sbi). Meanwhile, the bio completion callback is still executing:\nwhen it reaches page_array_free(sbi, ...), it dereferences\nsbi->page_array_slab — a destroyed slab cache — to call\nkmem_cache_free(), causing a use-after-free.\n\nThis is the same class of bug as CVE-2026-23234 (which fixed the\nequivalent race in f2fs_write_end_io() in data.c), but in the\ncompressed writeback completion path that was not covered by that fix.\n\nFix this by moving dec_page_count() to after page_array_free(), so\nthat all sbi accesses complete before the counter decrement that can\nunblock unmount. For non-last folios (where atomic_dec_return on\ncic->pending_pages is nonzero), dec_page_count is called immediately\nbefore returning — page_array_free is not reached on this path, so\nthere is no post-decrement sbi access. For the last folio,\npage_array_free runs while the F2FS_WB_CP_DATA counter is still\nnonzero (this folio has not yet decremented it), keeping sbi alive,\nand dec_page_count runs as the final operation.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-05-01 14:16:20","updated_at":"2026-06-01 17:16:56"},"problem_types":["CWE-416"],"metrics":[{"version":"3.1","source":"nvd@nist.gov","type":"Primary","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"}}],"references":[{"url":"https://git.kernel.org/stable/c/2c97dcb6147c8f7f25c629b93be1e69617de5d4a","name":"https://git.kernel.org/stable/c/2c97dcb6147c8f7f25c629b93be1e69617de5d4a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/57bc678f36ac03281e877c6b84877b43f964143f","name":"https://git.kernel.org/stable/c/57bc678f36ac03281e877c6b84877b43f964143f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/39d4ee19c1e7d753dd655aebee632271b171f43a","name":"https://git.kernel.org/stable/c/39d4ee19c1e7d753dd655aebee632271b171f43a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ef57cd3329b40c739b9a2e1a8a21ecc4171c6280","name":"https://git.kernel.org/stable/c/ef57cd3329b40c739b9a2e1a8a21ecc4171c6280","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c76cf339b87975ae5b2c06d2d774d5667d25a12a","name":"https://git.kernel.org/stable/c/c76cf339b87975ae5b2c06d2d774d5667d25a12a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f5154cf3ce1c8193f0c1891d3769f62740cfe6fe","name":"https://git.kernel.org/stable/c/f5154cf3ce1c8193f0c1891d3769f62740cfe6fe","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31702","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31702","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 57bc678f36ac03281e877c6b84877b43f964143f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 ef57cd3329b40c739b9a2e1a8a21ecc4171c6280 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 f5154cf3ce1c8193f0c1891d3769f62740cfe6fe git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 c76cf339b87975ae5b2c06d2d774d5667d25a12a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2026","cve_id":"31702","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"31702","cve":"CVE-2026-31702","epss":"0.000180000","percentile":"0.048290000","score_date":"2026-05-05","updated_at":"2026-05-06 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the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()\n\nIn f2fs_compress_write_end_io(), dec_page_count(sbi, type) can bring\nthe F2FS_WB_CP_DATA counter to zero, unblocking\nf2fs_wait_on_all_pages() in f2fs_put_super() on a concurrent unmount\nCPU. The unmount path then proceeds to call\nf2fs_destroy_page_array_cache(sbi), which destroys\nsbi->page_array_slab via kmem_cache_destroy(), and eventually\nkfree(sbi). Meanwhile, the bio completion callback is still executing:\nwhen it reaches page_array_free(sbi, ...), it dereferences\nsbi->page_array_slab — a destroyed slab cache — to call\nkmem_cache_free(), causing a use-after-free.\n\nThis is the same class of bug as CVE-2026-23234 (which fixed the\nequivalent race in f2fs_write_end_io() in data.c), but in the\ncompressed writeback completion path that was not covered by that fix.\n\nFix this by moving dec_page_count() to after page_array_free(), so\nthat all sbi accesses complete before the counter decrement that can\nunblock unmount. For non-last folios (where atomic_dec_return on\ncic->pending_pages is nonzero), dec_page_count is called immediately\nbefore returning — page_array_free is not reached on this path, so\nthere is no post-decrement sbi access. For the last folio,\npage_array_free runs while the F2FS_WB_CP_DATA counter is still\nnonzero (this folio has not yet decremented it), keeping sbi alive,\nand dec_page_count runs as the final operation."}],"providerMetadata":{"dateUpdated":"2026-06-01T16:13:44.047Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/57bc678f36ac03281e877c6b84877b43f964143f"},{"url":"https://git.kernel.org/stable/c/ef57cd3329b40c739b9a2e1a8a21ecc4171c6280"},{"url":"https://git.kernel.org/stable/c/f5154cf3ce1c8193f0c1891d3769f62740cfe6fe"},{"url":"https://git.kernel.org/stable/c/c76cf339b87975ae5b2c06d2d774d5667d25a12a"},{"url":"https://git.kernel.org/stable/c/2c97dcb6147c8f7f25c629b93be1e69617de5d4a"},{"url":"https://git.kernel.org/stable/c/39d4ee19c1e7d753dd655aebee632271b171f43a"}],"title":"f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31702","datePublished":"2026-05-01T13:56:01.601Z","dateReserved":"2026-03-09T15:48:24.132Z","dateUpdated":"2026-06-01T16:13:44.047Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-05-01 14:16:20","lastModifiedDate":"2026-06-01 17:16:56","problem_types":["CWE-416"],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","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":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.6","versionEndExcluding":"6.6.136","matchCriteriaId":"C8FF327A-4809-4F9C-B926-FF8D39DAAA1D"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.84","matchCriteriaId":"D4ECA0DE-AFF5-4688-B219-4CA2336CA5B7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.25","matchCriteriaId":"8B0A7E0E-F6D8-45DB-8CD9-01839FE40A6C"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"7.0.2","matchCriteriaId":"1BD58F1E-7C20-4C0D-92A2-FAC5CBFBE8A8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*","matchCriteriaId":"B1EF7059-E670-45F4-B422-54C40FA86390"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*","matchCriteriaId":"0D38F0BF-A728-4133-A358-D44A2F7EE6D6"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31702","Ordinal":"1","Title":"f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()","CVE":"CVE-2026-31702","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31702","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()\n\nIn f2fs_compress_write_end_io(), dec_page_count(sbi, type) can bring\nthe F2FS_WB_CP_DATA counter to zero, unblocking\nf2fs_wait_on_all_pages() in f2fs_put_super() on a concurrent unmount\nCPU. The unmount path then proceeds to call\nf2fs_destroy_page_array_cache(sbi), which destroys\nsbi->page_array_slab via kmem_cache_destroy(), and eventually\nkfree(sbi). Meanwhile, the bio completion callback is still executing:\nwhen it reaches page_array_free(sbi, ...), it dereferences\nsbi->page_array_slab — a destroyed slab cache — to call\nkmem_cache_free(), causing a use-after-free.\n\nThis is the same class of bug as CVE-2026-23234 (which fixed the\nequivalent race in f2fs_write_end_io() in data.c), but in the\ncompressed writeback completion path that was not covered by that fix.\n\nFix this by moving dec_page_count() to after page_array_free(), so\nthat all sbi accesses complete before the counter decrement that can\nunblock unmount. For non-last folios (where atomic_dec_return on\ncic->pending_pages is nonzero), dec_page_count is called immediately\nbefore returning — page_array_free is not reached on this path, so\nthere is no post-decrement sbi access. For the last folio,\npage_array_free runs while the F2FS_WB_CP_DATA counter is still\nnonzero (this folio has not yet decremented it), keeping sbi alive,\nand dec_page_count runs as the final operation.","Type":"Description","Title":"f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()"}]}}}