CVE-2026-64543 (GCVE-0-2026-64543)
Vulnerability from cvelistv5
Published
2026-07-27 20:10
Modified
2026-10-19 20:48
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: tipc: fix use-after-free of the discoverer in tipc_disc_rcv() bearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(), but tipc_disc_rcv() still dereferences b->disc in RX softirq under rcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv). L2 bearers are safe thanks to the synchronize_net() in tipc_disable_l2_media(), but the UDP bearer defers that call to the cleanup_bearer() workqueue, so the discoverer is freed with no grace period: BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149) Read of size 8 at addr ffff88802348b728 by task poc_tipc/184 <IRQ> tipc_disc_rcv (net/tipc/discover.c:149) tipc_rcv (net/tipc/node.c:2126) tipc_udp_recv (net/tipc/udp_media.c:391) udp_rcv (net/ipv4/udp.c:2643) ip_local_deliver_finish (net/ipv4/ip_input.c:241) </IRQ> Freed by task 181: kfree (mm/slub.c:6565) bearer_disable (net/tipc/bearer.c:418) tipc_nl_bearer_disable (net/tipc/bearer.c:1001) The bearer is freed with kfree_rcu(); free the discoverer the same way. Add an rcu_head to struct tipc_discoverer and free it and its skb from an RCU callback. Because the RCU callback (tipc_disc_free_rcu) lives in module text, a call_rcu() that is still pending when the tipc module is unloaded would invoke a freed function. Add an rcu_barrier() to tipc_exit() after the bearer subsystem has been torn down, so all pending discoverer callbacks have run before the module text goes away. Reachable from an unprivileged user namespace: the TIPCv2 genl family is netnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC and CONFIG_TIPC_MEDIA_UDP.
References
Impacted products
Vendor Product Version
Linux Linux Version: 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259
Version: 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259
Version: 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259
Version: 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259
Version: 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259
Version: 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259
Version: 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259
Version: 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix use-after-free of the discoverer in tipc_disc_rcv()\n\nbearer_disable() frees b-\u003edisc with tipc_disc_delete()\u0027s plain kfree(),\nbut tipc_disc_rcv() still dereferences b-\u003edisc in RX softirq under\nrcu_read_lock() (tipc_udp_recv -\u003e tipc_rcv -\u003e tipc_disc_rcv).\n\nL2 bearers are safe thanks to the synchronize_net() in\ntipc_disable_l2_media(), but the UDP bearer defers that call to the\ncleanup_bearer() workqueue, so the discoverer is freed with no grace\nperiod:\n\n BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149)\n Read of size 8 at addr ffff88802348b728 by task poc_tipc/184\n \u003cIRQ\u003e\n  tipc_disc_rcv (net/tipc/discover.c:149)\n  tipc_rcv (net/tipc/node.c:2126)\n  tipc_udp_recv (net/tipc/udp_media.c:391)\n  udp_rcv (net/ipv4/udp.c:2643)\n  ip_local_deliver_finish (net/ipv4/ip_input.c:241)\n \u003c/IRQ\u003e\n Freed by task 181:\n  kfree (mm/slub.c:6565)\n  bearer_disable (net/tipc/bearer.c:418)\n  tipc_nl_bearer_disable (net/tipc/bearer.c:1001)\n\nThe bearer is freed with kfree_rcu(); free the discoverer the same way.\nAdd an rcu_head to struct tipc_discoverer and free it and its skb from an\nRCU callback.\n\nBecause the RCU callback (tipc_disc_free_rcu) lives in module text, a\ncall_rcu() that is still pending when the tipc module is unloaded would\ninvoke a freed function. Add an rcu_barrier() to tipc_exit() after the\nbearer subsystem has been torn down, so all pending discoverer callbacks\nhave run before the module text goes away.\n\nReachable from an unprivileged user namespace: the TIPCv2 genl family is\nnetnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC\nand CONFIG_TIPC_MEDIA_UDP."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The free side is only reachable through the local TIPCv2 generic-netlink `BEARER_DISABLE` command (or netns teardown); a remote peer can supply the discovery packet that performs the use-after-free access but cannot itself cause `bearer_disable()` to run, so the complete attack requires local access.\nAC:L - The attacker controls both sides of the race \u2014 one thread floods TIPC discovery packets at the bearer\u0027s UDP port while another disables the bearer \u2014 and `bearer_disable()` clears `b-\u003eup` and then `kfree()`s the discoverer with no synchronization whatsoever, leaving a wide window that a multi-CPU packet flood hits reliably (a working PoC exists).\nPR:L - `tipc_genl_family` is `.netnsok = true` and the bearer enable/disable ops carry no `GENL_ADMIN_PERM` or other capability check, so an unprivileged user can do everything inside `unshare -Urn` after autoloading tipc via `socket(AF_TIPC, ...)`.\nUI:N - The attacking process performs both the bearer disable and the packet injection itself; no victim action or cooperating user is involved.\nS:U - The corruption stays within the kernel\u0027s own security authority \u2014 no VM, IOMMU, or hypervisor boundary is crossed.\nC:H - `d-\u003enet` is read from the freed slab object and dereferenced as a `struct net *`; after reclaiming the kmalloc-192 allocation with sprayed data the attacker gains a controlled-pointer dereference chain usable for arbitrary kernel memory disclosure.\nI:H - `msg_set_prevnode(buf_msg(d-\u003eskb), sugg_addr)` writes a wire-controlled 32-bit value through the dangling `d-\u003eskb` pointer, and `tipc_disc_add_dest()` takes a spinlock and increments a counter in freed memory \u2014 together a controlled-address/controlled-value write suitable for control-flow hijacking.\nA:H - The use-after-free reliably produces a KASAN slab-use-after-free in softirq context and, on production kernels, a corrupted-pointer dereference or spinlock manipulation on reclaimed memory leading to kernel panic."
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
        {
          "url": "https://git.kernel.org/stable/c/380413cdfd29fb9fa486c82889132b680c4983c5"
        },
        {
          "url": "https://git.kernel.org/stable/c/f05b3f4c78370469286879c765f5a1dd39dbcd32"
        },
        {
          "url": "https://git.kernel.org/stable/c/4da2ac7749411971e1b222b992da5a172ce45f98"
        },
        {
          "url": "https://git.kernel.org/stable/c/5e215bf1c47fdddf8203a0fe80a0ed594065f101"
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        {
          "url": "https://git.kernel.org/stable/c/ec7d54d8cc1723921d671e3272b427c96366506f"
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          "url": "https://git.kernel.org/stable/c/a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2"
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        {
          "url": "https://git.kernel.org/stable/c/1579342d71133da7f00daa02c75cebec7372097b"
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      ],
      "title": "tipc: fix use-after-free of the discoverer in tipc_disc_rcv()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64543",
    "datePublished": "2026-07-27T20:10:35.565Z",
    "dateReserved": "2026-07-19T15:36:31.795Z",
    "dateUpdated": "2026-10-19T20:48:39.735Z",
    "state": "PUBLISHED"
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side is only reachable through the local TIPCv2 generic-netlink `BEARER_DISABLE` command (or netns teardown); a remote peer can supply the discovery packet that performs the use-after-free access but cannot itself cause `bearer_disable()` to run, so the complete attack requires local access.\\nAC:L - The attacker controls both sides of the race \\u2014 one thread floods TIPC discovery packets at the bearer\u0027s UDP port while another disables the bearer \\u2014 and `bearer_disable()` clears `b-\u003eup` and then `kfree()`s the discoverer with no synchronization whatsoever, leaving a wide window that a multi-CPU packet flood hits reliably (a working PoC exists).\\nPR:L - `tipc_genl_family` is `.netnsok = true` and the bearer enable/disable ops carry no `GENL_ADMIN_PERM` or other capability check, so an unprivileged user can do everything inside `unshare -Urn` after autoloading tipc via `socket(AF_TIPC, ...)`.\\nUI:N - The attacking process performs both the bearer disable and the packet injection itself; no victim action or cooperating user is involved.\\nS:U - The corruption stays within the kernel\u0027s own security authority \\u2014 no VM, IOMMU, or hypervisor boundary is crossed.\\nC:H - `d-\u003enet` is read from the freed slab object and dereferenced as a `struct net *`; after reclaiming the kmalloc-192 allocation with sprayed data the attacker gains a controlled-pointer dereference chain usable for arbitrary kernel memory disclosure.\\nI:H - `msg_set_prevnode(buf_msg(d-\u003eskb), sugg_addr)` writes a wire-controlled 32-bit value through the dangling `d-\u003eskb` pointer, and `tipc_disc_add_dest()` takes a spinlock and increments a counter in freed memory \\u2014 together a controlled-address/controlled-value write suitable for control-flow hijacking.\\nA:H - The use-after-free reliably produces a KASAN slab-use-after-free in softirq context and, on production kernels, a corrupted-pointer dereference or spinlock manipulation on reclaimed memory leading 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\"ec7d54d8cc1723921d671e3272b427c96366506f\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"25b0b9c4e835ffaa65b61c3efe2e28acf84d0259\", \"lessThan\": \"a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"25b0b9c4e835ffaa65b61c3efe2e28acf84d0259\", \"lessThan\": \"b65289e1c3f352a9f92c6e19713ddd647e033253\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"25b0b9c4e835ffaa65b61c3efe2e28acf84d0259\", \"lessThan\": \"1579342d71133da7f00daa02c75cebec7372097b\", \"versionType\": \"git\"}], \"programFiles\": [\"net/tipc/core.c\", \"net/tipc/discover.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"4.17\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"4.17\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.10.265\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.216\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.183\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.145\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.97\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.18.40\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"7.1.5\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"7.1.*\"}, {\"status\": \"unaffected\", \"version\": \"7.2\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"net/tipc/core.c\", \"net/tipc/discover.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/380413cdfd29fb9fa486c82889132b680c4983c5\"}, {\"url\": \"https://git.kernel.org/stable/c/f05b3f4c78370469286879c765f5a1dd39dbcd32\"}, {\"url\": \"https://git.kernel.org/stable/c/4da2ac7749411971e1b222b992da5a172ce45f98\"}, {\"url\": \"https://git.kernel.org/stable/c/5e215bf1c47fdddf8203a0fe80a0ed594065f101\"}, {\"url\": \"https://git.kernel.org/stable/c/ec7d54d8cc1723921d671e3272b427c96366506f\"}, {\"url\": \"https://git.kernel.org/stable/c/a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2\"}, {\"url\": \"https://git.kernel.org/stable/c/b65289e1c3f352a9f92c6e19713ddd647e033253\"}, {\"url\": \"https://git.kernel.org/stable/c/1579342d71133da7f00daa02c75cebec7372097b\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\ntipc: fix use-after-free of the discoverer in tipc_disc_rcv()\\n\\nbearer_disable() frees b-\u003edisc with tipc_disc_delete()\u0027s plain kfree(),\\nbut tipc_disc_rcv() still dereferences b-\u003edisc in RX softirq under\\nrcu_read_lock() (tipc_udp_recv -\u003e tipc_rcv -\u003e tipc_disc_rcv).\\n\\nL2 bearers are safe thanks to the synchronize_net() in\\ntipc_disable_l2_media(), but the UDP bearer defers that call to the\\ncleanup_bearer() workqueue, so the discoverer is freed with no grace\\nperiod:\\n\\n BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149)\\n Read of size 8 at addr ffff88802348b728 by task poc_tipc/184\\n \u003cIRQ\u003e\\n  tipc_disc_rcv (net/tipc/discover.c:149)\\n  tipc_rcv (net/tipc/node.c:2126)\\n  tipc_udp_recv (net/tipc/udp_media.c:391)\\n  udp_rcv (net/ipv4/udp.c:2643)\\n  ip_local_deliver_finish (net/ipv4/ip_input.c:241)\\n \u003c/IRQ\u003e\\n Freed by task 181:\\n  kfree (mm/slub.c:6565)\\n  bearer_disable (net/tipc/bearer.c:418)\\n  tipc_nl_bearer_disable (net/tipc/bearer.c:1001)\\n\\nThe bearer is freed with kfree_rcu(); free the discoverer the same way.\\nAdd an rcu_head to struct tipc_discoverer and free it and its skb from an\\nRCU callback.\\n\\nBecause the RCU callback (tipc_disc_free_rcu) lives in module text, a\\ncall_rcu() that is still pending when the tipc module is unloaded would\\ninvoke a freed function. Add an rcu_barrier() to tipc_exit() after the\\nbearer subsystem has been torn down, so all pending discoverer callbacks\\nhave run before the module text goes away.\\n\\nReachable from an unprivileged user namespace: the TIPCv2 genl family is\\nnetnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC\\nand CONFIG_TIPC_MEDIA_UDP.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.265\", \"versionStartIncluding\": \"4.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.216\", \"versionStartIncluding\": \"4.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.183\", \"versionStartIncluding\": \"4.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.145\", \"versionStartIncluding\": \"4.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.97\", \"versionStartIncluding\": \"4.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.40\", \"versionStartIncluding\": \"4.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.1.5\", \"versionStartIncluding\": \"4.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.2\", \"versionStartIncluding\": \"4.17\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-19T16:28:28.342Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-64543\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T20:48:39.735Z\", \"dateReserved\": \"2026-07-19T15:36:31.795Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-07-27T20:10:35.565Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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