{"api_version":"1","generated_at":"2026-09-11T13:38:14+00:00","cve":"CVE-2026-80808","urls":{"html":"https://cve.report/CVE-2026-80808","api":"https://cve.report/api/cve/CVE-2026-80808.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-80808","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80808"},"summary":{"title":"ext4: stop retrying saturated xattr cache entries","description":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: stop retrying saturated xattr cache entries\n\next4_xattr_block_set() retries when a cache entry selected for reuse\nhas a saturated reference count after taking the buffer lock. The retry\nreturns to the mbcache lookup without making that entry ineligible, so\nit can select the same unusable entry indefinitely. A task spinning\nthere can hold the parent directory's i_rwsem and leave concurrent\nrmdir callers blocked.\n\nNormally a reusable entry has a reference count below\nEXT4_XATTR_REFCOUNT_MAX because the count and MBE_REUSABLE_B are\nupdated under the same buffer lock. A corrupted filesystem can violate\nthat invariant. The syzbot reproducer reports allocator and xattr\ncorruption before triggering this retry loop.\n\nCheck the untrusted on-disk count before incrementing it, avoiding\noverflow, and clear MBE_REUSABLE_B when it is already saturated. The\nnext lookup then skips the entry that was just proven unusable. This\nmirrors the normal transition at EXT4_XATTR_REFCOUNT_MAX; the release\npath marks the entry reusable again on the exact 1024-to-1023\ntransition.\n\nUsing the same QEMU harness and guest parameters, current unpatched\nLinux hung in 6 of 8 420-second trials with the do_rmdir signature;\nrepresentative NMI backtraces caught the owner spinning in\next4_xattr_block_set(). The patched kernel completed 28 of 28 trials\nwithout a hung-task report; the final twelve trials exercised the\nreviewed overflow-safe form of the change. syzbot's patch testing also\ncompleted without reproducing the hang.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-04 16:18:07","updated_at":"2026-09-04 16:18:07"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/dbd4aea175ad3c46436acb251e817b4374628072","name":"https://git.kernel.org/stable/c/dbd4aea175ad3c46436acb251e817b4374628072","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/889ec86464d261f026f6c334040cfc6c58c99d58","name":"https://git.kernel.org/stable/c/889ec86464d261f026f6c334040cfc6c58c99d58","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a40c45268f4358207aa9c53764fed2e05f62986a","name":"https://git.kernel.org/stable/c/a40c45268f4358207aa9c53764fed2e05f62986a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9","name":"https://git.kernel.org/stable/c/4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/54b6bd40898de7906acb2bccc9a96d1b8e6b4323","name":"https://git.kernel.org/stable/c/54b6bd40898de7906acb2bccc9a96d1b8e6b4323","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8865cd664484517703df5c18a965dc3227572b87","name":"https://git.kernel.org/stable/c/8865cd664484517703df5c18a965dc3227572b87","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/61631352a5b405c89be579de00903b72e6888aa4","name":"https://git.kernel.org/stable/c/61631352a5b405c89be579de00903b72e6888aa4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/119a2f053242ed75bdd2ebc95baf3ae7db6ccacf","name":"https://git.kernel.org/stable/c/119a2f053242ed75bdd2ebc95baf3ae7db6ccacf","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5","name":"https://git.kernel.org/stable/c/55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80808","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80808","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1a56cd972ce121b6cf2517a47a578782bbd2ec95 119a2f053242ed75bdd2ebc95baf3ae7db6ccacf git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1be97463696c7291a3e1547614e96432b0bd3add 61631352a5b405c89be579de00903b72e6888aa4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b 8865cd664484517703df5c18a965dc3227572b87 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b a40c45268f4358207aa9c53764fed2e05f62986a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.19.2 5.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.267 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.218 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.185 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.154 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.106 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.47 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.11 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.1 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":"80808","cve":"CVE-2026-80808","epss":"0.001950000","percentile":"0.092860000","score_date":"2026-09-07","updated_at":"2026-09-08 00:05:27"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/ext4/xattr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"119a2f053242ed75bdd2ebc95baf3ae7db6ccacf","status":"affected","version":"1a56cd972ce121b6cf2517a47a578782bbd2ec95","versionType":"git"},{"lessThan":"61631352a5b405c89be579de00903b72e6888aa4","status":"affected","version":"1be97463696c7291a3e1547614e96432b0bd3add","versionType":"git"},{"lessThan":"8865cd664484517703df5c18a965dc3227572b87","status":"affected","version":"65f8b80053a1b2fd602daa6814e62d6fa90e5e9b","versionType":"git"},{"lessThan":"a40c45268f4358207aa9c53764fed2e05f62986a","status":"affected","version":"65f8b80053a1b2fd602daa6814e62d6fa90e5e9b","versionType":"git"},{"lessThan":"889ec86464d261f026f6c334040cfc6c58c99d58","status":"affected","version":"65f8b80053a1b2fd602daa6814e62d6fa90e5e9b","versionType":"git"},{"lessThan":"4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9","status":"affected","version":"65f8b80053a1b2fd602daa6814e62d6fa90e5e9b","versionType":"git"},{"lessThan":"55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5","status":"affected","version":"65f8b80053a1b2fd602daa6814e62d6fa90e5e9b","versionType":"git"},{"lessThan":"dbd4aea175ad3c46436acb251e817b4374628072","status":"affected","version":"65f8b80053a1b2fd602daa6814e62d6fa90e5e9b","versionType":"git"},{"lessThan":"54b6bd40898de7906acb2bccc9a96d1b8e6b4323","status":"affected","version":"65f8b80053a1b2fd602daa6814e62d6fa90e5e9b","versionType":"git"},{"status":"affected","version":"98953044b3cdb2cb7d82e7365b659e2ed4f4ca4d","versionType":"git"},{"status":"affected","version":"af8ecc8d20e72130771cc076bce7fcf17ccda6c4","versionType":"git"},{"status":"affected","version":"c6fac5cf5a5098732623bcd00a8a3eb9f5465144","versionType":"git"},{"status":"affected","version":"96fa141fa295ae9428da73c56c9852053b575c04","versionType":"git"},{"lessThan":"5.10.267","status":"affected","version":"5.10.163","versionType":"semver"},{"lessThan":"5.15.218","status":"affected","version":"5.15.61","versionType":"semver"},{"lessThan":"4.20","status":"affected","version":"4.19.270","versionType":"semver"},{"lessThan":"5.5","status":"affected","version":"5.4.229","versionType":"semver"},{"lessThan":"5.19","status":"affected","version":"5.18.18","versionType":"semver"},{"lessThan":"5.20","status":"affected","version":"5.19.2","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/ext4/xattr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.0"},{"lessThan":"6.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.267","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.218","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.185","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.154","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.106","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.47","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.11","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.1","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":"5.10.267","versionStartIncluding":"5.10.163","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.218","versionStartIncluding":"5.15.61","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.185","versionStartIncluding":"6.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.154","versionStartIncluding":"6.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.106","versionStartIncluding":"6.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.47","versionStartIncluding":"6.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.11","versionStartIncluding":"6.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.1","versionStartIncluding":"6.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.270","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4.229","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.18.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19.2","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: stop retrying saturated xattr cache entries\n\next4_xattr_block_set() retries when a cache entry selected for reuse\nhas a saturated reference count after taking the buffer lock. The retry\nreturns to the mbcache lookup without making that entry ineligible, so\nit can select the same unusable entry indefinitely. A task spinning\nthere can hold the parent directory's i_rwsem and leave concurrent\nrmdir callers blocked.\n\nNormally a reusable entry has a reference count below\nEXT4_XATTR_REFCOUNT_MAX because the count and MBE_REUSABLE_B are\nupdated under the same buffer lock. A corrupted filesystem can violate\nthat invariant. The syzbot reproducer reports allocator and xattr\ncorruption before triggering this retry loop.\n\nCheck the untrusted on-disk count before incrementing it, avoiding\noverflow, and clear MBE_REUSABLE_B when it is already saturated. The\nnext lookup then skips the entry that was just proven unusable. This\nmirrors the normal transition at EXT4_XATTR_REFCOUNT_MAX; the release\npath marks the entry reusable again on the exact 1024-to-1023\ntransition.\n\nUsing the same QEMU harness and guest parameters, current unpatched\nLinux hung in 6 of 8 420-second trials with the do_rmdir signature;\nrepresentative NMI backtraces caught the owner spinning in\next4_xattr_block_set(). The patched kernel completed 28 of 28 trials\nwithout a hung-task report; the final twelve trials exercised the\nreviewed overflow-safe form of the change. syzbot's patch testing also\ncompleted without reproducing the hang."}],"providerMetadata":{"dateUpdated":"2026-09-04T15:13:28.562Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/119a2f053242ed75bdd2ebc95baf3ae7db6ccacf"},{"url":"https://git.kernel.org/stable/c/61631352a5b405c89be579de00903b72e6888aa4"},{"url":"https://git.kernel.org/stable/c/8865cd664484517703df5c18a965dc3227572b87"},{"url":"https://git.kernel.org/stable/c/a40c45268f4358207aa9c53764fed2e05f62986a"},{"url":"https://git.kernel.org/stable/c/889ec86464d261f026f6c334040cfc6c58c99d58"},{"url":"https://git.kernel.org/stable/c/4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9"},{"url":"https://git.kernel.org/stable/c/55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5"},{"url":"https://git.kernel.org/stable/c/dbd4aea175ad3c46436acb251e817b4374628072"},{"url":"https://git.kernel.org/stable/c/54b6bd40898de7906acb2bccc9a96d1b8e6b4323"}],"title":"ext4: stop retrying saturated xattr cache entries","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-80808","datePublished":"2026-09-04T15:13:28.562Z","dateReserved":"2026-08-26T14:34:25.794Z","dateUpdated":"2026-09-04T15:13:28.562Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-04 16:18:07","lastModifiedDate":"2026-09-04 16:18:07","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"80808","Ordinal":"1","Title":"ext4: stop retrying saturated xattr cache entries","CVE":"CVE-2026-80808","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"80808","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: stop retrying saturated xattr cache entries\n\next4_xattr_block_set() retries when a cache entry selected for reuse\nhas a saturated reference count after taking the buffer lock. The retry\nreturns to the mbcache lookup without making that entry ineligible, so\nit can select the same unusable entry indefinitely. A task spinning\nthere can hold the parent directory's i_rwsem and leave concurrent\nrmdir callers blocked.\n\nNormally a reusable entry has a reference count below\nEXT4_XATTR_REFCOUNT_MAX because the count and MBE_REUSABLE_B are\nupdated under the same buffer lock. A corrupted filesystem can violate\nthat invariant. The syzbot reproducer reports allocator and xattr\ncorruption before triggering this retry loop.\n\nCheck the untrusted on-disk count before incrementing it, avoiding\noverflow, and clear MBE_REUSABLE_B when it is already saturated. The\nnext lookup then skips the entry that was just proven unusable. This\nmirrors the normal transition at EXT4_XATTR_REFCOUNT_MAX; the release\npath marks the entry reusable again on the exact 1024-to-1023\ntransition.\n\nUsing the same QEMU harness and guest parameters, current unpatched\nLinux hung in 6 of 8 420-second trials with the do_rmdir signature;\nrepresentative NMI backtraces caught the owner spinning in\next4_xattr_block_set(). The patched kernel completed 28 of 28 trials\nwithout a hung-task report; the final twelve trials exercised the\nreviewed overflow-safe form of the change. syzbot's patch testing also\ncompleted without reproducing the hang.","Type":"Description","Title":"ext4: stop retrying saturated xattr cache entries"}]}}}