FKIE_CVE-2026-68169

Vulnerability from fkie_nvd - Published: 2026-08-10 13:20 - Updated: 2026-08-17 05:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: userspace: fix use-after-free in get_local_id In mptcp_pm_userspace_get_local_id(), the address entry is looked up under spinlock, but its id is read after dropping the lock. A concurrent deletion can free the entry between the unlock and the read, leading to UAF. The race window is narrow. It was reproduced only with a locally constructed stress test that repeatedly overlaps an MP_JOIN SYN with a MPTCP_PM_CMD_SUBFLOW_DESTROY request. However, the KASAN report below confirms that the race is reachable: [ 666.319376] BUG: KASAN: slab-use-after-free in mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319386] Read of size 1 at addr ffff888124845610 by task swapper/0/0 ... [ 666.319401] Call Trace: [ 666.319405] <IRQ> [ 666.319408] dump_stack_lvl+0x53/0x70 [ 666.319412] print_address_description.constprop.0+0x2c/0x3b0 [ 666.319418] print_report+0xbe/0x2b0 [ 666.319421] ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319423] kasan_report+0xce/0x100 [ 666.319426] ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319429] mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319433] mptcp_pm_get_local_id+0x371/0x440 ... [ 666.319821] Allocated by task 45539: [ 666.319844] kasan_save_stack+0x33/0x60 [ 666.319855] kasan_save_track+0x14/0x30 [ 666.319858] __kasan_kmalloc+0x8f/0xa0 [ 666.319863] __kmalloc_noprof+0x1e7/0x520 [ 666.319867] sock_kmalloc+0xdf/0x130 [ 666.319885] sock_kmemdup+0x1b/0x40 [ 666.319888] mptcp_userspace_pm_append_new_local_addr+0x261/0x500 [ 666.319910] mptcp_pm_nl_announce_doit+0x16a/0x610 ... [ 666.319967] Freed by task 45560: [ 666.319988] kasan_save_stack+0x33/0x60 [ 666.319991] kasan_save_track+0x14/0x30 [ 666.319994] kasan_save_free_info+0x3b/0x60 [ 666.319998] __kasan_slab_free+0x43/0x70 [ 666.320000] kfree+0x166/0x440 [ 666.320003] sock_kfree_s+0x1d/0x50 [ 666.320007] mptcp_userspace_pm_delete_local_addr.isra.0+0x157/0x200 [ 666.320011] mptcp_pm_nl_subflow_destroy_doit+0x51d/0xea0 Fix by copying the id into a local variable while still holding the lock, and use -1 as a "not found" sentinel.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/31ce5af66891f79998fb2e8b8df08e3c98fd72e3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/40dde4b5d98279471a70e5c8bb713182738c00d9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d2c3760b45f2f481a4dd4c5adef4a29dfabd948f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d64f6c02495f3fad674038cfa7ec049671b59e7b
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/pm_userspace.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "d2c3760b45f2f481a4dd4c5adef4a29dfabd948f",
              "status": "affected",
              "version": "ed34dfa19ddbd1e4c85a73636f8cba0211025ea4",
              "versionType": "git"
            },
            {
              "lessThan": "31ce5af66891f79998fb2e8b8df08e3c98fd72e3",
              "status": "affected",
              "version": "f012d796a6de662692159c539689e47e662853a8",
              "versionType": "git"
            },
            {
              "lessThan": "d64f6c02495f3fad674038cfa7ec049671b59e7b",
              "status": "affected",
              "version": "f012d796a6de662692159c539689e47e662853a8",
              "versionType": "git"
            },
            {
              "lessThan": "40dde4b5d98279471a70e5c8bb713182738c00d9",
              "status": "affected",
              "version": "f012d796a6de662692159c539689e47e662853a8",
              "versionType": "git"
            },
            {
              "lessThan": "9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9",
              "status": "affected",
              "version": "f012d796a6de662692159c539689e47e662853a8",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e373bfc8ec3d6496ec7e11dd7f4d087a44b1009a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "005a3ad289eb604216dcaa03646de36cb08624a0",
              "versionType": "git"
            },
            {
              "lessThan": "6.6.151",
              "status": "affected",
              "version": "6.6.18",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.79",
              "versionType": "semver"
            },
            {
              "lessThan": "6.8",
              "status": "affected",
              "version": "6.7.6",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/pm_userspace.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": "6.6.*",
              "status": "unaffected",
              "version": "6.6.151",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.103",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "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]  \u003cIRQ\u003e\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."
    }
  ],
  "id": "CVE-2026-68169",
  "lastModified": "2026-08-17T05:18:17.447",
  "metrics": {},
  "published": "2026-08-10T13:20:03.483",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/31ce5af66891f79998fb2e8b8df08e3c98fd72e3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/40dde4b5d98279471a70e5c8bb713182738c00d9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d2c3760b45f2f481a4dd4c5adef4a29dfabd948f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d64f6c02495f3fad674038cfa7ec049671b59e7b"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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