{"api_version":"1","generated_at":"2026-08-22T02:51:10+00:00","cve":"CVE-2026-74583","urls":{"html":"https://cve.report/CVE-2026-74583","api":"https://cve.report/api/cve/CVE-2026-74583.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74583","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74583"},"summary":{"title":"net/sched: cls_route: fix fastmap use-after-free on filter","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_route: fix fastmap use-after-free on filter\n\nThe route4 classifier maintains a 16-slot fastmap cache that stores raw\nstruct route4_filter pointers indexed by (id, iif). The reader\n(route4_classify) populates this cache via route4_set_fastmap() for every\nclassified packet that hits a filter. The writer (route4_delete,\nroute4_change) clears the cache via route4_reset_fastmap() before\nRCU-deferred kfree of the filter.\n\nThis creates a UAF race:\n 1. Reader walks the RCU-protected bucket chain, finds filter f\n 2. Writer unlinks f, calls route4_reset_fastmap(), then tcf_queue_work()\n 3. Reader calls route4_set_fastmap() and writes f into the cache\n    *after* the writer's reset, caching a pointer about to be freed\n 4. After the RCU grace period, kfree(f) executes\n 5. Next classified packet on the same (id, iif) tuple hits the stale\n    fastmap entry and reads f->res from freed memory\n\nReproduced with an mdelay(100) accelerator in route4_set_fastmap() and a\nconcurrent add/delete stress test (provided by both zdi and Santosh).\nBoth triggered KASAN slab-use-after-free reports in the route4 fastmap\npaths.\n\nFix:\nIntroduce a per-filter boolean dying flag to suppress stale fastmap\nrepublishing by in-flight readers.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-21 17:16:44","updated_at":"2026-08-21 17:16:44"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/7897198b26445b4009a057bda1986b94a99e5d5f","name":"https://git.kernel.org/stable/c/7897198b26445b4009a057bda1986b94a99e5d5f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0e7a8cf8895b06d07c7311f028eba16ad742b9bc","name":"https://git.kernel.org/stable/c/0e7a8cf8895b06d07c7311f028eba16ad742b9bc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b969984b2bdc85d721ce4047cd270cd37ec705a2","name":"https://git.kernel.org/stable/c/b969984b2bdc85d721ce4047cd270cd37ec705a2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/47d7f7051253bdc02b1d245d87e38f16d31a74df","name":"https://git.kernel.org/stable/c/47d7f7051253bdc02b1d245d87e38f16d31a74df","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/820f083c294ad6d319c02a7d43294f2ed2565139","name":"https://git.kernel.org/stable/c/820f083c294ad6d319c02a7d43294f2ed2565139","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ae9aff87025219005a2d16b4fe83d6f24643e50d","name":"https://git.kernel.org/stable/c/ae9aff87025219005a2d16b4fe83d6f24643e50d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5ec9001be6d0eb527251125632ec8fe88278897f","name":"https://git.kernel.org/stable/c/5ec9001be6d0eb527251125632ec8fe88278897f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a17f636c9330eac879822ce29f998e5abd1b72c1","name":"https://git.kernel.org/stable/c/a17f636c9330eac879822ce29f998e5abd1b72c1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74583","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74583","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1109c00547fc66df45b9ff923544be4c1e1bec13 7897198b26445b4009a057bda1986b94a99e5d5f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1109c00547fc66df45b9ff923544be4c1e1bec13 820f083c294ad6d319c02a7d43294f2ed2565139 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1109c00547fc66df45b9ff923544be4c1e1bec13 5ec9001be6d0eb527251125632ec8fe88278897f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1109c00547fc66df45b9ff923544be4c1e1bec13 b969984b2bdc85d721ce4047cd270cd37ec705a2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1109c00547fc66df45b9ff923544be4c1e1bec13 a17f636c9330eac879822ce29f998e5abd1b72c1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1109c00547fc66df45b9ff923544be4c1e1bec13 0e7a8cf8895b06d07c7311f028eba16ad742b9bc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1109c00547fc66df45b9ff923544be4c1e1bec13 ae9aff87025219005a2d16b4fe83d6f24643e50d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1109c00547fc66df45b9ff923544be4c1e1bec13 47d7f7051253bdc02b1d245d87e38f16d31a74df git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.18","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 3.18 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.265 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.216 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.183 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.152 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.104 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.45 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.9 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/sched/cls_route.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"7897198b26445b4009a057bda1986b94a99e5d5f","status":"affected","version":"1109c00547fc66df45b9ff923544be4c1e1bec13","versionType":"git"},{"lessThan":"820f083c294ad6d319c02a7d43294f2ed2565139","status":"affected","version":"1109c00547fc66df45b9ff923544be4c1e1bec13","versionType":"git"},{"lessThan":"5ec9001be6d0eb527251125632ec8fe88278897f","status":"affected","version":"1109c00547fc66df45b9ff923544be4c1e1bec13","versionType":"git"},{"lessThan":"b969984b2bdc85d721ce4047cd270cd37ec705a2","status":"affected","version":"1109c00547fc66df45b9ff923544be4c1e1bec13","versionType":"git"},{"lessThan":"a17f636c9330eac879822ce29f998e5abd1b72c1","status":"affected","version":"1109c00547fc66df45b9ff923544be4c1e1bec13","versionType":"git"},{"lessThan":"0e7a8cf8895b06d07c7311f028eba16ad742b9bc","status":"affected","version":"1109c00547fc66df45b9ff923544be4c1e1bec13","versionType":"git"},{"lessThan":"ae9aff87025219005a2d16b4fe83d6f24643e50d","status":"affected","version":"1109c00547fc66df45b9ff923544be4c1e1bec13","versionType":"git"},{"lessThan":"47d7f7051253bdc02b1d245d87e38f16d31a74df","status":"affected","version":"1109c00547fc66df45b9ff923544be4c1e1bec13","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/sched/cls_route.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"3.18"},{"lessThan":"3.18","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.265","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.216","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.183","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.152","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.104","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.45","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.9","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.265","versionStartIncluding":"3.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.216","versionStartIncluding":"3.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.183","versionStartIncluding":"3.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.152","versionStartIncluding":"3.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.104","versionStartIncluding":"3.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.45","versionStartIncluding":"3.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.9","versionStartIncluding":"3.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"3.18","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_route: fix fastmap use-after-free on filter\n\nThe route4 classifier maintains a 16-slot fastmap cache that stores raw\nstruct route4_filter pointers indexed by (id, iif). The reader\n(route4_classify) populates this cache via route4_set_fastmap() for every\nclassified packet that hits a filter. The writer (route4_delete,\nroute4_change) clears the cache via route4_reset_fastmap() before\nRCU-deferred kfree of the filter.\n\nThis creates a UAF race:\n 1. Reader walks the RCU-protected bucket chain, finds filter f\n 2. Writer unlinks f, calls route4_reset_fastmap(), then tcf_queue_work()\n 3. Reader calls route4_set_fastmap() and writes f into the cache\n    *after* the writer's reset, caching a pointer about to be freed\n 4. After the RCU grace period, kfree(f) executes\n 5. Next classified packet on the same (id, iif) tuple hits the stale\n    fastmap entry and reads f->res from freed memory\n\nReproduced with an mdelay(100) accelerator in route4_set_fastmap() and a\nconcurrent add/delete stress test (provided by both zdi and Santosh).\nBoth triggered KASAN slab-use-after-free reports in the route4 fastmap\npaths.\n\nFix:\nIntroduce a per-filter boolean dying flag to suppress stale fastmap\nrepublishing by in-flight readers."}],"providerMetadata":{"dateUpdated":"2026-08-21T16:31:55.886Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/7897198b26445b4009a057bda1986b94a99e5d5f"},{"url":"https://git.kernel.org/stable/c/820f083c294ad6d319c02a7d43294f2ed2565139"},{"url":"https://git.kernel.org/stable/c/5ec9001be6d0eb527251125632ec8fe88278897f"},{"url":"https://git.kernel.org/stable/c/b969984b2bdc85d721ce4047cd270cd37ec705a2"},{"url":"https://git.kernel.org/stable/c/a17f636c9330eac879822ce29f998e5abd1b72c1"},{"url":"https://git.kernel.org/stable/c/0e7a8cf8895b06d07c7311f028eba16ad742b9bc"},{"url":"https://git.kernel.org/stable/c/ae9aff87025219005a2d16b4fe83d6f24643e50d"},{"url":"https://git.kernel.org/stable/c/47d7f7051253bdc02b1d245d87e38f16d31a74df"}],"title":"net/sched: cls_route: fix fastmap use-after-free on filter","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74583","datePublished":"2026-08-21T16:31:55.886Z","dateReserved":"2026-08-15T05:44:03.918Z","dateUpdated":"2026-08-21T16:31:55.886Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-21 17:16:44","lastModifiedDate":"2026-08-21 17:16:44","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74583","Ordinal":"1","Title":"net/sched: cls_route: fix fastmap use-after-free on filter","CVE":"CVE-2026-74583","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74583","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_route: fix fastmap use-after-free on filter\n\nThe route4 classifier maintains a 16-slot fastmap cache that stores raw\nstruct route4_filter pointers indexed by (id, iif). The reader\n(route4_classify) populates this cache via route4_set_fastmap() for every\nclassified packet that hits a filter. The writer (route4_delete,\nroute4_change) clears the cache via route4_reset_fastmap() before\nRCU-deferred kfree of the filter.\n\nThis creates a UAF race:\n 1. Reader walks the RCU-protected bucket chain, finds filter f\n 2. Writer unlinks f, calls route4_reset_fastmap(), then tcf_queue_work()\n 3. Reader calls route4_set_fastmap() and writes f into the cache\n    *after* the writer's reset, caching a pointer about to be freed\n 4. After the RCU grace period, kfree(f) executes\n 5. Next classified packet on the same (id, iif) tuple hits the stale\n    fastmap entry and reads f->res from freed memory\n\nReproduced with an mdelay(100) accelerator in route4_set_fastmap() and a\nconcurrent add/delete stress test (provided by both zdi and Santosh).\nBoth triggered KASAN slab-use-after-free reports in the route4 fastmap\npaths.\n\nFix:\nIntroduce a per-filter boolean dying flag to suppress stale fastmap\nrepublishing by in-flight readers.","Type":"Description","Title":"net/sched: cls_route: fix fastmap use-after-free on filter"}]}}}