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CVE-2026-63911 (GCVE-0-2026-63911)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-08-05 12:37
VLAI
Title
xfrm: iptfs: reset runtime state when cloning SAs
Summary
In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: reset runtime state when cloning SAs iptfs_clone_state() clones the IPTFS mode data with kmemdup(). This copies runtime objects which must not be shared with the original SA, including the embedded sk_buff_head, hrtimers, spinlock, and in-flight reassembly/reorder state. If xfrm_state_migrate() fails after clone_state() but before the later init_state() call has reinitialized those fields, the cloned state can be destroyed by xfrm_state_gc_task() with list and timer state copied from the original SA. With queued packets this lets the clone splice and free skbs owned by the original IPTFS queue, leading to use-after-free and double-free reports in iptfs_destroy_state() and skb release paths. Reinitialize the clone's runtime state before publishing it through x->mode_data. Because clone_state() now publishes a destroyable mode_data object before init_state(), take the mode callback module reference there. Avoid taking it again from __iptfs_init_state() for the same object.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 0e4fbf013fa566f274ce9b4ce698c75b1f998c52 , < 9327252e04626d4bb02ca8c0c108fbe8eabf0c5a (git)
Affected: 0e4fbf013fa566f274ce9b4ce698c75b1f998c52 , < dfb9f6cbfa9826655a49698cf90eb800fce2178e (git)
Affected: 0e4fbf013fa566f274ce9b4ce698c75b1f998c52 , < 7f83d174073234839aea176f265e517e0d50a1d2 (git)
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Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.12 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
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          "product": "Linux",
          "programFiles": [
            "net/xfrm/xfrm_iptfs.c"
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: iptfs: reset runtime state when cloning SAs\n\niptfs_clone_state() clones the IPTFS mode data with kmemdup(). This\ncopies runtime objects which must not be shared with the original SA,\nincluding the embedded sk_buff_head, hrtimers, spinlock, and in-flight\nreassembly/reorder state.\n\nIf xfrm_state_migrate() fails after clone_state() but before the later\ninit_state() call has reinitialized those fields, the cloned state can be\ndestroyed by xfrm_state_gc_task() with list and timer state copied from the\noriginal SA. With queued packets this lets the clone splice and free skbs\nowned by the original IPTFS queue, leading to use-after-free and\ndouble-free reports in iptfs_destroy_state() and skb release paths.\n\nReinitialize the clone\u0027s runtime state before publishing it through\nx-\u003emode_data. Because clone_state() now publishes a destroyable mode_data\nobject before init_state(), take the mode callback module reference there.\nAvoid taking it again from __iptfs_init_state() for the same object."
        }
      ],
      "metrics": [
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          "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 bug is reached only through local XFRM SA migration via netlink XFRM_MSG_MIGRATE or PF_KEY SADB_X_MIGRATE, not by processing remote network packets alone.\nAC:L - On systems with IPTFS and XFRM_MIGRATE enabled, an attacker who controls the migrate request can reliably queue skbs on the SA and force a post-clone migration failure to trigger the shared-queue teardown.\nPR:L - All XFRM migrate operations require CAP_NET_ADMIN on the target network namespace, which unprivileged users can obtain inside a user namespace via unshare.\nUI:N - Exploitation requires no victim interaction beyond the attacker\u2019s own netlink/PF_KEY operations and traffic through an SA they control.\nS:U - Impact is kernel memory corruption and privilege escalation within the same kernel security authority, not a cross-VM or cross-IOMMU boundary escape.\nC:H - The bug is a use-after-free on sk_buff objects where the clone\u2019s destroy path frees skbs still owned by the live original IPTFS queue, enabling arbitrary kernel memory read primitives.\nI:H - Shared queue/timer state corruption and skb double-free provide exploitable heap corruption that can be leveraged for arbitrary kernel writes or code execution.\nA:H - The vulnerability causes kernel oops/panic from UAF and double-free in skb release paths, and can be used for repeatable denial of service against the host."
            }
          ]
        }
      ],
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        "dateUpdated": "2026-08-05T12:37:05.089Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/9327252e04626d4bb02ca8c0c108fbe8eabf0c5a"
        },
        {
          "url": "https://git.kernel.org/stable/c/dfb9f6cbfa9826655a49698cf90eb800fce2178e"
        },
        {
          "url": "https://git.kernel.org/stable/c/7f83d174073234839aea176f265e517e0d50a1d2"
        }
      ],
      "title": "xfrm: iptfs: reset runtime state when cloning SAs",
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        "engine": "bippy-1.2.0"
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    }
  },
  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63911",
    "datePublished": "2026-07-19T14:55:16.496Z",
    "dateReserved": "2026-07-19T07:54:57.020Z",
    "dateUpdated": "2026-08-05T12:37:05.089Z",
    "state": "PUBLISHED"
  },
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    },
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-07-21T21:13:46+00:00",
      "cve": "CVE-2026-63911",
      "id": "CVE-2026-63911",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: xfrm: iptfs: reset runtime state when cloning SAs",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63911.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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