CVE-2026-31406 (GCVE-0-2026-31406)
Vulnerability from cvelistv5
Published
2026-04-06 07:38
Modified
2026-08-05 12:22
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: xfrm: Fix work re-schedule after cancel in xfrm_nat_keepalive_net_fini() After cancel_delayed_work_sync() is called from xfrm_nat_keepalive_net_fini(), xfrm_state_fini() flushes remaining states via __xfrm_state_delete(), which calls xfrm_nat_keepalive_state_updated() to re-schedule nat_keepalive_work. The following is a simple race scenario: cpu0 cpu1 cleanup_net() [Round 1] ops_undo_list() xfrm_net_exit() xfrm_nat_keepalive_net_fini() cancel_delayed_work_sync(nat_keepalive_work); xfrm_state_fini() xfrm_state_flush() xfrm_state_delete(x) __xfrm_state_delete(x) xfrm_nat_keepalive_state_updated(x) schedule_delayed_work(nat_keepalive_work); rcu_barrier(); net_complete_free(); net_passive_dec(net); llist_add(&net->defer_free_list, &defer_free_list); cleanup_net() [Round 2] rcu_barrier(); net_complete_free() kmem_cache_free(net_cachep, net); nat_keepalive_work() // on freed net To prevent this, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync().
References
Impacted products
Vendor Product Version
Linux Linux Version: f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae
Version: f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae
Version: f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae
Version: f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/xfrm/xfrm_nat_keepalive.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "32d0f44c2f14d60fe8e920e69a28c11051543ec1",
              "status": "affected",
              "version": "f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae",
              "versionType": "git"
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            {
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/xfrm/xfrm_nat_keepalive.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.11"
            },
            {
              "lessThan": "6.11",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.80",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.21",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.80",
                  "versionStartIncluding": "6.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.21",
                  "versionStartIncluding": "6.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.11",
                  "versionStartIncluding": "6.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.11",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: Fix work re-schedule after cancel in xfrm_nat_keepalive_net_fini()\n\nAfter cancel_delayed_work_sync() is called from\nxfrm_nat_keepalive_net_fini(), xfrm_state_fini() flushes remaining\nstates via __xfrm_state_delete(), which calls\nxfrm_nat_keepalive_state_updated() to re-schedule nat_keepalive_work.\n\nThe following is a simple race scenario:\n\n           cpu0                             cpu1\n\ncleanup_net() [Round 1]\n  ops_undo_list()\n    xfrm_net_exit()\n      xfrm_nat_keepalive_net_fini()\n        cancel_delayed_work_sync(nat_keepalive_work);\n      xfrm_state_fini()\n        xfrm_state_flush()\n          xfrm_state_delete(x)\n            __xfrm_state_delete(x)\n              xfrm_nat_keepalive_state_updated(x)\n                schedule_delayed_work(nat_keepalive_work);\n  rcu_barrier();\n  net_complete_free();\n  net_passive_dec(net);\n    llist_add(\u0026net-\u003edefer_free_list, \u0026defer_free_list);\n\ncleanup_net() [Round 2]\n  rcu_barrier();\n  net_complete_free()\n    kmem_cache_free(net_cachep, net);\n                                     nat_keepalive_work()\n                                       // on freed net\n\nTo prevent this, cancel_delayed_work_sync() is replaced with\ndisable_delayed_work_sync()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "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 vulnerable path is reached through local namespace lifecycle and NETLINK_XFRM state configuration, not by remote packet processing. An attacker can create an affected outbound ESP-in-UDP XFRM state locally and tear down the network namespace.\nAC:L - The attacker controls creation of the NAT keepalive state and repeated teardown of the network namespace; the work reschedule after cancel is a direct consequence of the cleanup ordering. Any scheduling race can be retried and influenced locally, so there are no hard external conditions.\nPR:L - XFRM netlink operations require CAP_NET_ADMIN in the target network namespace. This is reachable by an unprivileged local user through a user namespace plus network namespace where they hold CAP_NET_ADMIN.\nUI:N - No victim action is required after the attacker runs local code. The attacker can configure the state and trigger namespace cleanup directly.\nS:U - The vulnerability corrupts kernel memory within the same kernel security authority. It is a standard local kernel compromise scenario, not a VM or hardware boundary escape.\nC:H - This is a use-after-free of a network namespace embedded delayed_work object and subsequent XFRM/netns state access. Per kernel scoring guidance, UAFs are treated as enabling high confidentiality impact.\nI:H - The dangling work item can operate on freed and potentially reclaimed kernel memory, giving a plausible path to memory corruption and control-flow compromise. Per kernel scoring guidance, UAFs are treated as high integrity impact.\nA:H - At minimum, executing delayed work on a freed struct net can dereference freed XFRM state and namespace data, causing an oops or panic. Repeated local triggering can reliably deny service."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:22:15.395Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/32d0f44c2f14d60fe8e920e69a28c11051543ec1"
        },
        {
          "url": "https://git.kernel.org/stable/c/2255ed6adbc3100d2c4a83abd9d0396d04b87792"
        },
        {
          "url": "https://git.kernel.org/stable/c/21f2fc49ca6faa393c31da33b8a4e6c41fc84c13"
        },
        {
          "url": "https://git.kernel.org/stable/c/daf8e3b253aa760ff9e96c7768a464bc1d6b3c90"
        }
      ],
      "title": "xfrm: Fix work re-schedule after cancel in xfrm_nat_keepalive_net_fini()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31406",
    "datePublished": "2026-04-06T07:38:18.840Z",
    "dateReserved": "2026-03-09T15:48:24.086Z",
    "dateUpdated": "2026-08-05T12:22:15.395Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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