CVE-2026-53212 (GCVE-0-2026-53212)
Vulnerability from cvelistv5
Published
2026-06-25 08:39
Modified
2026-08-05 12:34
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: netfilter: nft_tunnel: fix use-after-free on object destroy nft_tunnel_obj_destroy() calls metadata_dst_free() which directly kfree()s the metadata_dst, ignoring the dst_entry refcount. Packets that took a reference via dst_hold() in nft_tunnel_obj_eval() and are still queued (e.g. in a netem qdisc) are left with a dangling pointer. When these packets are eventually dequeued, dst_release() operates on freed memory. Replace metadata_dst_free() with dst_release() so the metadata_dst is freed only after all references are dropped. The dst subsystem already handles metadata_dst cleanup in dst_destroy() when DST_METADATA is set.
References
Impacted products
Vendor Product Version
Linux Linux Version: af308b94a2a4a5a27bec9028354c4df444a7c8ba
Version: af308b94a2a4a5a27bec9028354c4df444a7c8ba
Version: af308b94a2a4a5a27bec9028354c4df444a7c8ba
Version: af308b94a2a4a5a27bec9028354c4df444a7c8ba
Version: af308b94a2a4a5a27bec9028354c4df444a7c8ba
Version: af308b94a2a4a5a27bec9028354c4df444a7c8ba
Version: af308b94a2a4a5a27bec9028354c4df444a7c8ba
Version: af308b94a2a4a5a27bec9028354c4df444a7c8ba
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nft_tunnel.c"
          ],
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          "vendor": "Linux",
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              "version": "0",
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "versionEndExcluding": "7.1",
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_tunnel: fix use-after-free on object destroy\n\nnft_tunnel_obj_destroy() calls metadata_dst_free() which directly\nkfree()s the metadata_dst, ignoring the dst_entry refcount. Packets\nthat took a reference via dst_hold() in nft_tunnel_obj_eval() and\nare still queued (e.g. in a netem qdisc) are left with a dangling\npointer. When these packets are eventually dequeued, dst_release()\noperates on freed memory.\n\nReplace metadata_dst_free() with dst_release() so the metadata_dst\nis freed only after all references are dropped. The dst subsystem\nalready handles metadata_dst cleanup in dst_destroy() when\nDST_METADATA is set."
        }
      ],
      "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 nft_tunnel object is created, referenced, and destroyed through nf_tables netlink operations and packet processing configured locally via nftables/netdev hooks. Remote packets may help populate a queue, but exploitation requires local control of nftables transactions.\nAC:L - The attacker can set up the tunnel object/rule, arrange queued packets such as with netem, and delete the rule/object sequence under their control. No uncontrollable race or rare external condition is required.\nPR:L - nfnetlink requires CAP_NET_ADMIN in the socket network namespace, and nftables/netfilter is reachable by an unprivileged local user through user and network namespaces on typical affected systems. This is low privilege rather than real init-namespace root.\nUI:N - No victim user action is required after the attacker has local execution. The trigger is performed through attacker-issued netlink configuration and packet generation/dequeue.\nS:U - The bug corrupts kernel networking memory and can lead to local kernel privilege escalation within the same security authority. It is not a VM escape, IOMMU bypass, or other CVSS scope-changing boundary crossing.\nC:H - This is a heap use-after-free of a metadata_dst referenced from queued skbs, and similar nf_tables UAFs are exploitable for kernel memory disclosure. Following the higher-severity rule for UAFs, confidentiality impact is high.\nI:H - The freed dst/metadata object can be reclaimed and later operated on through dst_release and related networking paths, giving a plausible route to memory corruption and control-flow or arbitrary write exploitation. Following the kernel UAF guidance, integrity impact is high.\nA:H - Even without full exploitation, dequeuing packets with a dangling dst pointer can cause a kernel oops, panic, or memory-corruption crash. Availability impact is therefore high."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:34:10.386Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/349df61526d2e39decc685d246202e3e284cfe05"
        },
        {
          "url": "https://git.kernel.org/stable/c/55b79b1ae42372012413ce0413181d26679b17ef"
        },
        {
          "url": "https://git.kernel.org/stable/c/5e9ee18b27fde88cb6148202b33916c66693fe82"
        },
        {
          "url": "https://git.kernel.org/stable/c/8767fe4079affa74314d7eb3220e700150289842"
        },
        {
          "url": "https://git.kernel.org/stable/c/fda6573a46ad24f35348e024905ee5bdf729797e"
        },
        {
          "url": "https://git.kernel.org/stable/c/941d7394efda5e054e2d6f3e0dd0f6a9ba19aaa3"
        },
        {
          "url": "https://git.kernel.org/stable/c/f9a0e4b61054cde89a2a77845293c726cc07cc43"
        },
        {
          "url": "https://git.kernel.org/stable/c/c32b26aaa2f9216520a38b3f4bfeec846eb3eb8a"
        }
      ],
      "title": "netfilter: nft_tunnel: fix use-after-free on object destroy",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53212",
    "datePublished": "2026-06-25T08:39:16.888Z",
    "dateReserved": "2026-06-09T07:44:35.391Z",
    "dateUpdated": "2026-08-05T12:34:10.386Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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