CVE-2026-98230 (GCVE-0-2026-98230)
Vulnerability from cvelistv5
Published
2026-10-06 08:45
Modified
2026-10-19 09:16
Severity ?
7.0 (High) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: xfrm: use hlist_del_init_rcu for state_cache and state_cache_input Commit 14acf9652e56 ("xfrm: defensively unhash xfrm_state lists in __xfrm_state_delete") converted bydst/bysrc/byseq/byspi from hlist_del_rcu() to hlist_del_init_rcu() so that a second __xfrm_state_delete() on the same object becomes a no-op rather than a write through LIST_POISON pprev. It missed state_cache and state_cache_input, which kept hlist_del_rcu(): - hlist_del_rcu() leaves pprev = LIST_POISON2 (non-NULL), so hlist_unhashed() returns false. - hlist_del_init_rcu() leaves pprev = NULL, so hlist_unhashed() returns true. A second __xfrm_state_delete() therefore enters __hlist_del() on the already-deleted state_cache/state_cache_input nodes and does WRITE_ONCE(*pprev, next) through LIST_POISON2 — a write use-after-free once the slab is reused. The corruption can in turn cause a subsequent hlist_for_each_entry_rcu traversal to follow a dangling next pointer, producing the read use-after-free reported in xfrm_input_state_lookup(). Switch state_cache and state_cache_input to hlist_del_init_rcu() to match the other four lists, closing the write use-after-free and, with it, the read use-after-free it spawns.
References
Impacted products
Vendor Product Version
Linux Linux Version: aa48a18fdb0911572d133057cd579db704b87da4
Version: 0045e3d80613cc7174dc15f189ee6fc4e73b9365
Version: 0045e3d80613cc7174dc15f189ee6fc4e73b9365
Version: 0045e3d80613cc7174dc15f189ee6fc4e73b9365
Version: 5e4334dc39443645415450163ff5ff1ee7e79784
Version: 6.12.13   ≤
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
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          "programFiles": [
            "net/xfrm/xfrm_state.c"
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: use hlist_del_init_rcu for state_cache and state_cache_input\n\nCommit 14acf9652e56 (\"xfrm: defensively unhash xfrm_state lists in\n__xfrm_state_delete\") converted bydst/bysrc/byseq/byspi from\nhlist_del_rcu() to hlist_del_init_rcu() so that a second\n__xfrm_state_delete() on the same object becomes a no-op rather than a\nwrite through LIST_POISON pprev. It missed state_cache and\nstate_cache_input, which kept hlist_del_rcu():\n\n- hlist_del_rcu() leaves pprev = LIST_POISON2 (non-NULL), so\n  hlist_unhashed() returns false.\n- hlist_del_init_rcu() leaves pprev = NULL, so hlist_unhashed()\n  returns true.\n\nA second __xfrm_state_delete() therefore enters __hlist_del() on the\nalready-deleted state_cache/state_cache_input nodes and does\nWRITE_ONCE(*pprev, next) through LIST_POISON2 \u2014 a write use-after-free\nonce the slab is reused. The corruption can in turn cause a subsequent\nhlist_for_each_entry_rcu traversal to follow a dangling next pointer,\nproducing the read use-after-free reported in xfrm_input_state_lookup().\n\nSwitch state_cache and state_cache_input to hlist_del_init_rcu() to\nmatch the other four lists, closing the write use-after-free and, with\nit, the read use-after-free it spawns."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bad unlink is in __xfrm_state_delete(), reached when SAs are removed via XFRM_MSG_DELSA/FLUSHSA/EXPIRE over NETLINK_XFRM or the af_key socket, or via xfrm_timer_handler expiry. ESP packets only walk state_cache_input in xfrm_input_state_lookup() and carry no malformed data that causes the double unlink, so the vector is local.\nAC:H - A second unlink needs __xfrm_state_delete() to see a non-DEAD state that was already removed, but every caller holds x-\u003elock and checks km.state. The only path found that skips the VALID check is mlx5e_ipsec_handle_event(), which calls xfrm_state_check_expire() on a hardware hard-limit event and needs mlx5 packet offload, so the attacker cannot reliably arrange it.\nPR:L - Adding, expiring and flushing SAs over NETLINK_XFRM needs CAP_NET_ADMIN only in the user namespace that owns the netns. An unprivileged user gets it with unshare -Urn, and each netns has its own state_cache_input percpu lists and xfrm_state_lock.\nUI:N - The attacker drives the SA lifecycle (add, expire, delete, flush) and the traffic that fills the state caches themselves. No other user has to do anything.\nS:U - The corrupted hlist nodes are inside struct xfrm_state in kernel slab memory, so the impact stays within the kernel\u0027s own security authority.\nC:H - After the stale-pprev unlink, the state_cache_input chain can keep a freed xfrm_state, which hlist_for_each_entry_rcu in xfrm_input_state_lookup() then dereferences (the read UAF the commit reports). With slab reuse, an attacker can control the contents of that object.\nI:H - __hlist_del() on an already-unlinked state_cache/state_cache_input node does WRITE_ONCE(*pprev, next) through a stale pointer, a write use-after-free into reused slab memory that corrupts RCU hash-chain linkage.\nA:H - Writing through LIST_POISON2, or walking the corrupted per-CPU state_cache_input or policy state_cache_list chain, causes a general protection fault or KASAN oops in softirq or netns cleanup context, which takes down the kernel."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:16:02.121Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/fb38fb7420d5f7192f9e2b6ac835ede149cd7ac5"
        },
        {
          "url": "https://git.kernel.org/stable/c/4748c27e2e6a1969e02f1df46e62f79d2799b80b"
        },
        {
          "url": "https://git.kernel.org/stable/c/9b74a47a4cbd0d29faff4f3b199212c73e6b6220"
        },
        {
          "url": "https://git.kernel.org/stable/c/2afb8dc1f4390f164db8352f8e685e126e9db566"
        }
      ],
      "title": "xfrm: use hlist_del_init_rcu for state_cache and state_cache_input",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98230",
    "datePublished": "2026-10-06T08:45:04.548Z",
    "dateReserved": "2026-09-25T10:25:14.328Z",
    "dateUpdated": "2026-10-19T09:16:02.121Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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