CVE-2026-68323

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: tipc: serialize udp bearer replicast list updates tipc_udp_rcast_add() and cleanup_bearer() both update ub->rcast.list with list_add_rcu() / list_del_rcu(), but nothing serializes them. The add runs from the encap receive softirq (via tipc_udp_rcast_disc()) without rtnl_lock(), so it can race the cleanup delete and corrupt the list: list_del corruption. prev->next should be ffff8880298d7ab8, but was ffff88802449ad38. (prev=ffff888027e3ec98) kernel BUG at lib/list_debug.c:62! RIP: __list_del_entry_valid_or_report+0x17a/0x200 Workqueue: events cleanup_bearer Call Trace: cleanup_bearer (net/tipc/udp_media.c:811) process_one_work (kernel/workqueue.c:3302) worker_thread (kernel/workqueue.c:3466) The bearer can be enabled from an unprivileged user namespace, as the TIPCv2 generic-netlink ops carry no GENL_ADMIN_PERM. Add a spinlock to struct udp_bearer and take it around the list_add_rcu() in tipc_udp_rcast_add() and the list_del_rcu() loop in cleanup_bearer() so the two writers can no longer corrupt the list. Reject a duplicate peer under the same lock before allocating, and remove tipc_udp_is_known_peer(). The old lockless pre-check in tipc_udp_rcast_disc() was racy: two softirqs discovering the same peer could both find it absent and add it twice. cleanup_bearer() runs from a workqueue after tipc_udp_disable() clears the bearer's up bit, so an encap softirq can still reach tipc_udp_rcast_add() and add a peer after cleanup_bearer() has already emptied the list, leaking that entry when the bearer is freed. Mark the bearer disabled under rcast_lock once the list is emptied and refuse further additions.

Severity

HIGH

CVSS score

7.8 (v3.1)

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-08-10 13:20:22.443000

Last modified

2026-10-30 13:19:43.547000

View original CVE JSON

{
  "id": "CVE-2026-68323",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-08-10T13:20:22.443",
  "lastModified": "2026-10-30T13:19:43.547",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: serialize udp bearer replicast list updates\n\ntipc_udp_rcast_add() and cleanup_bearer() both update ub->rcast.list with\nlist_add_rcu() / list_del_rcu(), but nothing serializes them. The add runs\nfrom the encap receive softirq (via tipc_udp_rcast_disc()) without\nrtnl_lock(), so it can race the cleanup delete and corrupt the list:\n\n  list_del corruption. prev->next should be ffff8880298d7ab8,\n    but was ffff88802449ad38. (prev=ffff888027e3ec98)\n  kernel BUG at lib/list_debug.c:62!\n  RIP: __list_del_entry_valid_or_report+0x17a/0x200\n  Workqueue: events cleanup_bearer\n  Call Trace:\n   cleanup_bearer (net/tipc/udp_media.c:811)\n   process_one_work (kernel/workqueue.c:3302)\n   worker_thread (kernel/workqueue.c:3466)\n\nThe bearer can be enabled from an unprivileged user namespace, as the\nTIPCv2 generic-netlink ops carry no GENL_ADMIN_PERM.\n\nAdd a spinlock to struct udp_bearer and take it around the list_add_rcu()\nin tipc_udp_rcast_add() and the list_del_rcu() loop in cleanup_bearer() so\nthe two writers can no longer corrupt the list.\n\nReject a duplicate peer under the same lock before allocating, and remove\ntipc_udp_is_known_peer(). The old lockless pre-check in\ntipc_udp_rcast_disc() was racy: two softirqs discovering the same peer\ncould both find it absent and add it twice.\n\ncleanup_bearer() runs from a workqueue after tipc_udp_disable() clears the\nbearer's up bit, so an encap softirq can still reach tipc_udp_rcast_add()\nand add a peer after cleanup_bearer() has already emptied the list, leaking\nthat entry when the bearer is freed. Mark the bearer disabled under\nrcast_lock once the list is emptied and refuse further additions."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "net/tipc/udp_media.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "ef20cd4dd1633987bcf46ac34ace2c8af212361f",
              "lessThan": "c148aec60ef1e806cbc9da44b3d89409df998ade",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "ef20cd4dd1633987bcf46ac34ace2c8af212361f",
              "lessThan": "3ff6b534d20824cddab99c81ea3bd1144e635626",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "ef20cd4dd1633987bcf46ac34ace2c8af212361f",
              "lessThan": "3ff143a884a19bfcf3aebd999b02274fe44f46f3",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "ef20cd4dd1633987bcf46ac34ace2c8af212361f",
              "lessThan": "5d3cea7d41dc72073fea6f879815c9b57c3b330d",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "ef20cd4dd1633987bcf46ac34ace2c8af212361f",
              "lessThan": "d70c81001df9320d3445e664428a1d408b5ba896",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "ef20cd4dd1633987bcf46ac34ace2c8af212361f",
              "lessThan": "350e592ff4e30e48ffb55e142d11a73e63f4869c",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "net/tipc/udp_media.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "4.9",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "4.9",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.191",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.160",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.114",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.57",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.1.6",
              "lessThanOrEqual": "7.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-10-16T15:47:07.182932Z",
          "id": "CVE-2026-68323",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-362"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/350e592ff4e30e48ffb55e142d11a73e63f4869c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/3ff143a884a19bfcf3aebd999b02274fe44f46f3",
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d70c81001df9320d3445e664428a1d408b5ba896",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}