CVE-2026-92489 (GCVE-0-2026-92489)
Vulnerability from cvelistv5
Published
2026-09-17 16:10
Modified
2026-10-19 09:03
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: xfrm: Fix skb double-free in xfrm_dev_direct_output() A return value other than 1 from local_out() means that the skb has been consumed or its ownership was transferred. xfrm_dev_direct_output() nevertheless frees the skb on this path, causing a double-free when netfilter drops the packet and invalidating any other owner. Return the local_out() result directly, matching the ownership handling in xfrm_output_resume().
References
Impacted products
Vendor Product Version
Linux Linux Version: bfb9b9404a53a72524ce695551755117e9d3deb0
Version: a0395e96831adee8ffa016bf958e4dce9ece656e
Version: 5eddd76ec2fd1988f0a3450fde9730b10dd22992
Version: 5eddd76ec2fd1988f0a3450fde9730b10dd22992
Version: 5eddd76ec2fd1988f0a3450fde9730b10dd22992
Version: d1d673a5bede3767252cff19c0ab1e5387c6f43f
Version: 6.6.85   ≤
Version: 6.12.21   ≤
Version: 6.13.9   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/xfrm/xfrm_output.c"
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        {
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          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "6.6.85",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.110",
                  "versionStartIncluding": "6.12.21",
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                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: Fix skb double-free in xfrm_dev_direct_output()\n\nA return value other than 1 from local_out() means that the skb has been\nconsumed or its ownership was transferred. xfrm_dev_direct_output()\nnevertheless frees the skb on this path, causing a double-free when\nnetfilter drops the packet and invalidating any other owner.\n\nReturn the local_out() result directly, matching the ownership handling\nin xfrm_output_resume()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - A received IPv4/IPv6 packet that ip_forward()/ip6_forward() passes through xfrm4_route_forward()/xfrm6_route_forward() reaches xfrm4_output()/xfrm6_output() then xfrm_output(); for an XFRM_DEV_OFFLOAD_PACKET tunnel SA with skb-\u003esk NULL, that forwarded inner IP packet is what xfrm_dev_direct_output() processes.\nAC:L - xfrm_dev_direct_output() calls nf_reset_ct() then dst-\u003eops-\u003elocal_out (__ip_local_out/__ip6_local_out), so NF_INET_LOCAL_OUT consumes the skb on DROP/QUEUE/STOLEN. The attacker owns the forwarded packet and can force that verdict (iptables/nft DROP, or nf_conntrack_in() NF_DROP when resolve_normal_ct() fails after flooding new 5-tuples); no race is required.\nPR:N - ip_forward() and ip6_forward() take the skb with no socket or credentials; XFRM matching is only the received packet\u0027s IP selectors, not an authenticated session. CAP_NET_ADMIN is needed on the victim to install the packet-offload SA, not for the attacker who sends the inner packet.\nUI:N - The attacker triggers the bug only by sending IP packets that an already-configured packet-offload tunnel gateway forwards into xfrm_dev_direct_output(); no victim mount, open, or confirmation is required at exploit time.\nS:U - The sk_buff double-free in xfrm_dev_direct_output() corrupts kernel heap in the same kernel that performs IPsec output and is not a KVM/Xen guest-to-host escape or an IOMMU/DMA boundary bypass.\nC:H - When local_out() returns != 1, nf_hook_slow() has already kfree_skb_reason()\u0027d the skb on NF_DROP (or another owner holds it); the extra kfree_skb() in xfrm_dev_direct_output() is a sk_buff slab double-free that can be reclaimed with crafted packets to read kernel memory.\nI:H - The same sk_buff double-free after __ip_local_out()/__ip6_local_out() transfers ownership lets the attacker reallocate the freed object and obtain a kernel write and control-flow hijack primitive, not a crash-only integrity effect.\nA:H - The extra kfree_skb() in xfrm_dev_direct_output() when local_out() has already consumed the skb corrupts the sk_buff cache and causes a kernel oops or panic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:03:55.784Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/621871b696b108026bf4b44ed4085ffa2102f417"
        },
        {
          "url": "https://git.kernel.org/stable/c/bc9297796bfdcc8d9609236e54519a4f38737aac"
        },
        {
          "url": "https://git.kernel.org/stable/c/02deb637e965950148752a304dd1471212dd6470"
        },
        {
          "url": "https://git.kernel.org/stable/c/56a347950e661c1a7f8f31c43a2ea53c2323b6f4"
        },
        {
          "url": "https://git.kernel.org/stable/c/2aed51fc58d9ce450e2c116efb956160fd06fa02"
        }
      ],
      "title": "xfrm: Fix skb double-free in xfrm_dev_direct_output()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-92489",
    "datePublished": "2026-09-17T16:10:04.126Z",
    "dateReserved": "2026-09-16T12:21:13.871Z",
    "dateUpdated": "2026-10-19T09:03:55.784Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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