{"id":"CVE-2026-68169","state":"PUBLISHED","title":"mptcp: pm: userspace: fix use-after-free in get_local_id","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: userspace: fix use-after-free in get_local_id\n\nIn mptcp_pm_userspace_get_local_id(), the address entry is looked up under\nspinlock, but its id is read after dropping the lock. A concurrent deletion\ncan free the entry between the unlock and the read, leading to UAF.\n\nThe race window is narrow. It was reproduced only with a locally\nconstructed stress test that repeatedly overlaps an MP_JOIN SYN with a\nMPTCP_PM_CMD_SUBFLOW_DESTROY request.\n\nHowever, the KASAN report below confirms that the race is reachable:\n\n  [  666.319376] BUG: KASAN: slab-use-after-free in mptcp_userspace_pm_get_local_id+0x1dc/0x1f0\n  [  666.319386] Read of size 1 at addr ffff888124845610 by task swapper/0/0\n  ...\n  [  666.319401] Call Trace:\n  [  666.319405]  <IRQ>\n  [  666.319408]  dump_stack_lvl+0x53/0x70\n  [  666.319412]  print_address_description.constprop.0+0x2c/0x3b0\n  [  666.319418]  print_report+0xbe/0x2b0\n  [  666.319421]  ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0\n  [  666.319423]  kasan_report+0xce/0x100\n  [  666.319426]  ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0\n  [  666.319429]  mptcp_userspace_pm_get_local_id+0x1dc/0x1f0\n  [  666.319433]  mptcp_pm_get_local_id+0x371/0x440\n  ...\n  [  666.319821] Allocated by task 45539:\n  [  666.319844]  kasan_save_stack+0x33/0x60\n  [  666.319855]  kasan_save_track+0x14/0x30\n  [  666.319858]  __kasan_kmalloc+0x8f/0xa0\n  [  666.319863]  __kmalloc_noprof+0x1e7/0x520\n  [  666.319867]  sock_kmalloc+0xdf/0x130\n  [  666.319885]  sock_kmemdup+0x1b/0x40\n  [  666.319888]  mptcp_userspace_pm_append_new_local_addr+0x261/0x500\n  [  666.319910]  mptcp_pm_nl_announce_doit+0x16a/0x610\n  ...\n  [  666.319967] Freed by task 45560:\n  [  666.319988]  kasan_save_stack+0x33/0x60\n  [  666.319991]  kasan_save_track+0x14/0x30\n  [  666.319994]  kasan_save_free_info+0x3b/0x60\n  [  666.319998]  __kasan_slab_free+0x43/0x70\n  [  666.320000]  kfree+0x166/0x440\n  [  666.320003]  sock_kfree_s+0x1d/0x50\n  [  666.320007]  mptcp_userspace_pm_delete_local_addr.isra.0+0x157/0x200\n  [  666.320011]  mptcp_pm_nl_subflow_destroy_doit+0x51d/0xea0\n\nFix by copying the id into a local variable while still holding the lock,\nand use -1 as a \"not found\" sentinel.","publishedAt":"2026-08-10T11:59:38.177Z","updatedAt":"2026-08-23T12:46:03.401Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e373bfc8ec3d6496ec7e11dd7f4d087a44b1009a","status":"affected","lessThan":"8ce48d2879aafc0e7a6f8bfc3613c0ba979ec6f5","versionType":"git"},{"version":"ed34dfa19ddbd1e4c85a73636f8cba0211025ea4","status":"affected","lessThan":"d2c3760b45f2f481a4dd4c5adef4a29dfabd948f","versionType":"git"},{"version":"f012d796a6de662692159c539689e47e662853a8","status":"affected","lessThan":"31ce5af66891f79998fb2e8b8df08e3c98fd72e3","versionType":"git"},{"version":"f012d796a6de662692159c539689e47e662853a8","status":"affected","lessThan":"d64f6c02495f3fad674038cfa7ec049671b59e7b","versionType":"git"},{"version":"f012d796a6de662692159c539689e47e662853a8","status":"affected","lessThan":"40dde4b5d98279471a70e5c8bb713182738c00d9","versionType":"git"},{"version":"f012d796a6de662692159c539689e47e662853a8","status":"affected","lessThan":"9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9","versionType":"git"},{"version":"005a3ad289eb604216dcaa03646de36cb08624a0","status":"affected","versionType":"git"},{"version":"6.1.79","status":"affected","lessThan":"6.1.184","versionType":"semver"},{"version":"6.6.18","status":"affected","lessThan":"6.6.151","versionType":"semver"},{"version":"6.7.6","status":"affected","lessThan":"6.8","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/pm_userspace.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.1.184","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/pm_userspace.c"]}],"references":["https://git.kernel.org/stable/c/8ce48d2879aafc0e7a6f8bfc3613c0ba979ec6f5","https://git.kernel.org/stable/c/d2c3760b45f2f481a4dd4c5adef4a29dfabd948f","https://git.kernel.org/stable/c/31ce5af66891f79998fb2e8b8df08e3c98fd72e3","https://git.kernel.org/stable/c/d64f6c02495f3fad674038cfa7ec049671b59e7b","https://git.kernel.org/stable/c/40dde4b5d98279471a70e5c8bb713182738c00d9","https://git.kernel.org/stable/c/9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/68xxx/CVE-2026-68169.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-68169","state":"PUBLISHED","datePublished":"2026-08-10T11:59:38.177Z","dateUpdated":"2026-08-23T12:46:03.401Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-30T09:28:09.372Z"},"containers":{"cna":{"title":"mptcp: pm: userspace: fix use-after-free in get_local_id","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: userspace: fix use-after-free in get_local_id\n\nIn mptcp_pm_userspace_get_local_id(), the address entry is looked up under\nspinlock, but its id is read after dropping the lock. A concurrent deletion\ncan free the entry between the unlock and the read, leading to UAF.\n\nThe race window is narrow. It was reproduced only with a locally\nconstructed stress test that repeatedly overlaps an MP_JOIN SYN with a\nMPTCP_PM_CMD_SUBFLOW_DESTROY request.\n\nHowever, the KASAN report below confirms that the race is reachable:\n\n  [  666.319376] BUG: KASAN: slab-use-after-free in mptcp_userspace_pm_get_local_id+0x1dc/0x1f0\n  [  666.319386] Read of size 1 at addr ffff888124845610 by task swapper/0/0\n  ...\n  [  666.319401] Call Trace:\n  [  666.319405]  <IRQ>\n  [  666.319408]  dump_stack_lvl+0x53/0x70\n  [  666.319412]  print_address_description.constprop.0+0x2c/0x3b0\n  [  666.319418]  print_report+0xbe/0x2b0\n  [  666.319421]  ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0\n  [  666.319423]  kasan_report+0xce/0x100\n  [  666.319426]  ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0\n  [  666.319429]  mptcp_userspace_pm_get_local_id+0x1dc/0x1f0\n  [  666.319433]  mptcp_pm_get_local_id+0x371/0x440\n  ...\n  [  666.319821] Allocated by task 45539:\n  [  666.319844]  kasan_save_stack+0x33/0x60\n  [  666.319855]  kasan_save_track+0x14/0x30\n  [  666.319858]  __kasan_kmalloc+0x8f/0xa0\n  [  666.319863]  __kmalloc_noprof+0x1e7/0x520\n  [  666.319867]  sock_kmalloc+0xdf/0x130\n  [  666.319885]  sock_kmemdup+0x1b/0x40\n  [  666.319888]  mptcp_userspace_pm_append_new_local_addr+0x261/0x500\n  [  666.319910]  mptcp_pm_nl_announce_doit+0x16a/0x610\n  ...\n  [  666.319967] Freed by task 45560:\n  [  666.319988]  kasan_save_stack+0x33/0x60\n  [  666.319991]  kasan_save_track+0x14/0x30\n  [  666.319994]  kasan_save_free_info+0x3b/0x60\n  [  666.319998]  __kasan_slab_free+0x43/0x70\n  [  666.320000]  kfree+0x166/0x440\n  [  666.320003]  sock_kfree_s+0x1d/0x50\n  [  666.320007]  mptcp_userspace_pm_delete_local_addr.isra.0+0x157/0x200\n  [  666.320011]  mptcp_pm_nl_subflow_destroy_doit+0x51d/0xea0\n\nFix by copying the id into a local variable while still holding the lock,\nand use -1 as a \"not found\" sentinel."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e373bfc8ec3d6496ec7e11dd7f4d087a44b1009a","status":"affected","lessThan":"8ce48d2879aafc0e7a6f8bfc3613c0ba979ec6f5","versionType":"git"},{"version":"ed34dfa19ddbd1e4c85a73636f8cba0211025ea4","status":"affected","lessThan":"d2c3760b45f2f481a4dd4c5adef4a29dfabd948f","versionType":"git"},{"version":"f012d796a6de662692159c539689e47e662853a8","status":"affected","lessThan":"31ce5af66891f79998fb2e8b8df08e3c98fd72e3","versionType":"git"},{"version":"f012d796a6de662692159c539689e47e662853a8","status":"affected","lessThan":"d64f6c02495f3fad674038cfa7ec049671b59e7b","versionType":"git"},{"version":"f012d796a6de662692159c539689e47e662853a8","status":"affected","lessThan":"40dde4b5d98279471a70e5c8bb713182738c00d9","versionType":"git"},{"version":"f012d796a6de662692159c539689e47e662853a8","status":"affected","lessThan":"9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9","versionType":"git"},{"version":"005a3ad289eb604216dcaa03646de36cb08624a0","status":"affected","versionType":"git"},{"version":"6.1.79","status":"affected","lessThan":"6.1.184","versionType":"semver"},{"version":"6.6.18","status":"affected","lessThan":"6.6.151","versionType":"semver"},{"version":"6.7.6","status":"affected","lessThan":"6.8","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/pm_userspace.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.1.184","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/pm_userspace.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/8ce48d2879aafc0e7a6f8bfc3613c0ba979ec6f5"},{"url":"https://git.kernel.org/stable/c/d2c3760b45f2f481a4dd4c5adef4a29dfabd948f"},{"url":"https://git.kernel.org/stable/c/31ce5af66891f79998fb2e8b8df08e3c98fd72e3"},{"url":"https://git.kernel.org/stable/c/d64f6c02495f3fad674038cfa7ec049671b59e7b"},{"url":"https://git.kernel.org/stable/c/40dde4b5d98279471a70e5c8bb713182738c00d9"},{"url":"https://git.kernel.org/stable/c/9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-23T12:46:03.401Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.79","versionEndExcluding":"6.1.184"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.18","versionEndExcluding":"6.6.151"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.12.103"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.18.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7.6"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}