CVE-2026-97602 (GCVE-0-2026-97602)
Vulnerability from cvelistv5
Published
2026-09-25 10:22
Modified
2026-10-19 09:10
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: inet: frags: invalidate queues before flushing them fqdir_pre_exit() flushes the skbs from incomplete queues without changing their completion state. A fragment which found a queue before high_thresh was cleared can then acquire the queue lock and reuse stale reassembly metadata. A queue concurrently killed after fqdir->dead is set can instead become INET_FRAG_COMPLETE|INET_FRAG_HASH_DEAD while still holding its old skbs; skipping it because it is complete leaves those references behind until asynchronous fqdir teardown. For IPv6, stale metadata can make ip6_frag_reasm() use the old nhoffset with a new skb and access memory out of bounds. The resulting heap corruption can be leveraged for local privilege escalation when unprivileged network namespaces are available. Unflushed fragments can also keep conntrack references alive after the conntrack per-net cleanup point. Kill each incomplete queue, then flush every queue still owned by the dying rhashtable. HASH_DEAD identifies that ownership, while complete queues without it are already owned by another destroy path and must be left alone. Releasing a timer reference removed by inet_frag_kill() is deferred to inet_frag_putn(), after the queue lock is dropped. KASAN report: BUG: KASAN: slab-out-of-bounds in ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2)) Write of size 1 at addr ff110001039c6e00 by task poc/771 Call Trace: ? ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2)) ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2)) ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479 (discriminator 5)) ip6_input_finish (net/ipv6/ip6_input.c:534) ipv6_rcv (include/net/dst.h:480 (discriminator 3) net/ipv6/ip6_input.c:119 (discriminator 3) net/ipv6/ip6_input.c:109 (discriminator 3) include/linux/netfilter.h:325 (discriminator 3) include/linux/netfilter.h:319 (discriminator 3) net/ipv6/ip6_input.c:351 (discriminator 3)) packet_sendmsg (net/packet/af_packet.c:3110 net/packet/af_packet.c:3142) __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880) The buggy address belongs to the object at ff110001039c6b40 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 0 bytes to the right of allocated 704-byte region [ff110001039c6b40, ff110001039c6e00) BUG: KASAN: slab-out-of-bounds in ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1)) Read of size 1 at addr ff110001039c6e08 by task poc/771 Call Trace: ? ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1)) ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1)) ip6_input_finish (net/ipv6/ip6_input.c:534) ipv6_rcv (include/net/dst.h:480 (discriminator 3) net/ipv6/ip6_input.c:119 (discriminator 3) net/ipv6/ip6_input.c:109 (discriminator 3) include/linux/netfilter.h:325 (discriminator 3) include/linux/netfilter.h:319 (discriminator 3) net/ipv6/ip6_input.c:351 (discriminator 3)) packet_sendmsg (net/packet/af_packet.c:3110 net/packet/af_packet.c:3142) __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880) packet_sendmsg (net/packet/af_packet.c:2959 net/packet/af_packet.c:3053 net/packet/af_packet.c:3142) __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880) The buggy address belongs to the object at ff110001039c6b40 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 8 bytes to the right of allocated 704-byte region [ff110001039c6b40, ff110001039c6e00)
References
Impacted products
Vendor Product Version
Linux Linux Version: 22ee4010866da81aeee08e1ea3fddbe418feb212
Version: 543555954b1ee8d1903a7020324efb41b0c97428
Version: c70df25214ac9b32b53e18e6ae3b8f073ffa6903
Version: 006a5035b495dec008805df249f92c22c89c3d2e
Version: 006a5035b495dec008805df249f92c22c89c3d2e
Version: 6.6.143   ≤
Version: 6.12.93   ≤
Version: 6.18.3   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/inet_fragment.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
            },
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            {
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            {
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              "status": "affected",
              "version": "6.18.3",
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/inet_fragment.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "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": "6.6.158",
                  "versionStartIncluding": "6.6.143",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "6.12.93",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "6.18.3",
                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "7.2.7",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
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                  "versionEndExcluding": "7.3",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ninet: frags: invalidate queues before flushing them\n\nfqdir_pre_exit() flushes the skbs from incomplete queues without\nchanging their completion state. A fragment which found a queue before\nhigh_thresh was cleared can then acquire the queue lock and reuse stale\nreassembly metadata. A queue concurrently killed after fqdir-\u003edead is\nset can instead become INET_FRAG_COMPLETE|INET_FRAG_HASH_DEAD while\nstill holding its old skbs; skipping it because it is complete leaves\nthose references behind until asynchronous fqdir teardown.\n\nFor IPv6, stale metadata can make ip6_frag_reasm() use the old\nnhoffset with a new skb and access memory out of bounds. The resulting\nheap corruption can be leveraged for local privilege escalation when\nunprivileged network namespaces are available. Unflushed fragments can\nalso keep conntrack references alive after the conntrack per-net\ncleanup point.\n\nKill each incomplete queue, then flush every queue still owned by the\ndying rhashtable. HASH_DEAD identifies that ownership, while complete\nqueues without it are already owned by another destroy path and must be\nleft alone. Releasing a timer reference removed by inet_frag_kill() is\ndeferred to inet_frag_putn(), after the queue lock is dropped.\n\nKASAN report:\n\n  BUG: KASAN: slab-out-of-bounds in ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))\n  Write of size 1 at addr ff110001039c6e00 by task poc/771\n  Call Trace:\n  ? ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))\n  ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))\n  ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479 (discriminator 5))\n  ip6_input_finish (net/ipv6/ip6_input.c:534)\n  ipv6_rcv (include/net/dst.h:480 (discriminator 3) net/ipv6/ip6_input.c:119 (discriminator 3) net/ipv6/ip6_input.c:109 (discriminator 3) include/linux/netfilter.h:325 (discriminator 3) include/linux/netfilter.h:319 (discriminator 3) net/ipv6/ip6_input.c:351 (discriminator 3))\n  packet_sendmsg (net/packet/af_packet.c:3110 net/packet/af_packet.c:3142)\n  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)\n  The buggy address belongs to the object at ff110001039c6b40\n  which belongs to the cache skbuff_small_head of size 704\n  The buggy address is located 0 bytes to the right of\n  allocated 704-byte region [ff110001039c6b40, ff110001039c6e00)\n\n  BUG: KASAN: slab-out-of-bounds in ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))\n  Read of size 1 at addr ff110001039c6e08 by task poc/771\n  Call Trace:\n  ? ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))\n  ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))\n  ip6_input_finish (net/ipv6/ip6_input.c:534)\n  ipv6_rcv (include/net/dst.h:480 (discriminator 3) net/ipv6/ip6_input.c:119 (discriminator 3) net/ipv6/ip6_input.c:109 (discriminator 3) include/linux/netfilter.h:325 (discriminator 3) include/linux/netfilter.h:319 (discriminator 3) net/ipv6/ip6_input.c:351 (discriminator 3))\n  packet_sendmsg (net/packet/af_packet.c:3110 net/packet/af_packet.c:3142)\n  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)\n  packet_sendmsg (net/packet/af_packet.c:2959 net/packet/af_packet.c:3053 net/packet/af_packet.c:3142)\n  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)\n  The buggy address belongs to the object at ff110001039c6b40\n  which belongs to the cache skbuff_small_head of size 704\n  The buggy address is located 8 bytes to the right of\n  allocated 704-byte region [ff110001039c6b40, ff110001039c6e00)"
        }
      ],
      "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 - fqdir_pre_exit() only runs from the pernet pre_exit hooks (ipv6_frags_pre_exit_net, ipv4_frags_pre_exit_net, nf_ct_net_pre_exit) while a network namespace is being torn down. A remote sender cannot tear down a netns. The reporter\u0027s KASAN trace injects the fragments locally with packet_sendmsg into ipv6_rcv inside the attacker\u0027s own namespace.\nAC:L - The attacker controls both sides of the race. They send IPv6 fragments into their own netns from threads, then destroy that netns by dropping its last reference. A fragment that found the queue in inet_frag_find() before high_thresh was zeroed then takes fq-\u003elock after the flush, so the attacker can retry this at will.\nPR:L - Creating a network namespace and opening an AF_PACKET socket in it both need CAP_NET_RAW or CAP_NET_ADMIN, which unshare -Urn grants to an unprivileged user. The fix commit itself says this path is exploitable when unprivileged network namespaces are available.\nUI:N - The attacker creates the namespace, sends the fragments and triggers the teardown. No other user has to do anything.\nS:U - This is kernel heap corruption that leads to local privilege escalation inside the same kernel. No VM, IOMMU or other authority boundary is crossed.\nC:H - ip6_frag_reasm() reuses a stale fq-\u003enhoffset with a new skb. KASAN shows a slab out-of-bounds read past a 704-byte skbuff_small_head object, and this heap corruption can be shaped into memory disclosure.\nI:H - skb_network_header(skb)[nhoff] = ... in ip6_frag_reasm() writes at the stale nhoffset. KASAN shows it writing past the end of an skbuff_small_head allocation, and the fix commit states this out-of-bounds write can be leveraged for privilege escalation.\nA:H - The out-of-bounds write corrupts the kernel heap and can crash the host. Unflushed fragments also keep conntrack references alive past the per-net cleanup point, so the whole machine can go down."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:10:06.270Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ff83367cda8eefbd62007ef1dff4f8104226d18a"
        },
        {
          "url": "https://git.kernel.org/stable/c/b9d77f1652e79e58eac48430d0431c329137efcc"
        },
        {
          "url": "https://git.kernel.org/stable/c/7cb5f4643a7fcdbfbee1fad3cdfc678add62d378"
        },
        {
          "url": "https://git.kernel.org/stable/c/bf3d6c44c84c57e8a4bb7f40ad95b64f9b0198ba"
        },
        {
          "url": "https://git.kernel.org/stable/c/b824476c56a153934c67c9e0f873e1fd967743d6"
        }
      ],
      "title": "inet: frags: invalidate queues before flushing them",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97602",
    "datePublished": "2026-09-25T10:22:15.389Z",
    "dateReserved": "2026-09-24T16:01:01.158Z",
    "dateUpdated": "2026-10-19T09:10:06.270Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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