FKIE_CVE-2026-45840

Vulnerability from fkie_nvd - Published: 2026-05-27 11:16 - Updated: 2026-06-26 18:56
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: openvswitch: cap upcall PID array size and pre-size vport replies The vport netlink reply helpers allocate a fixed-size skb with nlmsg_new(NLMSG_DEFAULT_SIZE, ...) but serialize the full upcall PID array via ovs_vport_get_upcall_portids(). Since ovs_vport_set_upcall_portids() accepts any non-zero multiple of sizeof(u32) with no upper bound, a CAP_NET_ADMIN user can install a PID array large enough to overflow the reply buffer, causing nla_put() to fail with -EMSGSIZE and hitting BUG_ON(err < 0). On systems with unprivileged user namespaces enabled (e.g., Ubuntu default), this is reachable via unshare -Urn since OVS vport mutation operations use GENL_UNS_ADMIN_PERM. kernel BUG at net/openvswitch/datapath.c:2414! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI CPU: 1 UID: 0 PID: 65 Comm: poc Not tainted 7.0.0-rc7-00195-geb216e422044 #1 RIP: 0010:ovs_vport_cmd_set+0x34c/0x400 Call Trace: <TASK> genl_family_rcv_msg_doit (net/netlink/genetlink.c:1116) genl_rcv_msg (net/netlink/genetlink.c:1194) netlink_rcv_skb (net/netlink/af_netlink.c:2550) genl_rcv (net/netlink/genetlink.c:1219) netlink_unicast (net/netlink/af_netlink.c:1344) netlink_sendmsg (net/netlink/af_netlink.c:1894) __sys_sendto (net/socket.c:2206) __x64_sys_sendto (net/socket.c:2209) do_syscall_64 (arch/x86/entry/syscall_64.c:63) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) </TASK> Kernel panic - not syncing: Fatal exception Reject attempts to set more PIDs than nr_cpu_ids in ovs_vport_set_upcall_portids(), and pre-compute the worst-case reply size in ovs_vport_cmd_msg_size() based on that bound, similar to the existing ovs_dp_cmd_msg_size(). nr_cpu_ids matches the cap already used by the per-CPU dispatch configuration on the datapath side (ovs_dp_cmd_fill_info() serialises at most nr_cpu_ids PIDs), so the two sides stay consistent.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1d6c02b86329883aa467a3a61f8d34369db73a2fPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2091c6aa0df6aba47deb5c8ab232b1cb60af3519Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8d59b80e69dddb665eb2de36e62859ab2073470ePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b39f763d720d623218bc1d95ace6855d7b474e81Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d9e47e29aacb9f8a9d59feb6ab5b128a9bbb40b0Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f99ac36b5d7c719d08a69fcdecce40f78a874e15Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f9ef3db77a383d66847fd082c2b437d8ae4d9c63Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fa6e90bc443bed8dc0d55bc5ea5b27ffdfe37704Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/openvswitch/datapath.c",
            "net/openvswitch/vport.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            "net/openvswitch/vport.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "version": "3.17"
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              "version": "0",
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              "status": "unaffected",
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              "status": "unaffected",
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              "versionType": "semver"
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              "status": "unaffected",
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              "status": "unaffected",
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              "status": "unaffected",
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      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: cap upcall PID array size and pre-size vport replies\n\nThe vport netlink reply helpers allocate a fixed-size skb with\nnlmsg_new(NLMSG_DEFAULT_SIZE, ...) but serialize the full upcall PID\narray via ovs_vport_get_upcall_portids().  Since\novs_vport_set_upcall_portids() accepts any non-zero multiple of\nsizeof(u32) with no upper bound, a CAP_NET_ADMIN user can install a PID\narray large enough to overflow the reply buffer, causing nla_put() to\nfail with -EMSGSIZE and hitting BUG_ON(err \u003c 0).  On systems with\nunprivileged user namespaces enabled (e.g., Ubuntu default), this is\nreachable via unshare -Urn since OVS vport mutation operations use\nGENL_UNS_ADMIN_PERM.\n\n kernel BUG at net/openvswitch/datapath.c:2414!\n Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n CPU: 1 UID: 0 PID: 65 Comm: poc Not tainted 7.0.0-rc7-00195-geb216e422044 #1\n RIP: 0010:ovs_vport_cmd_set+0x34c/0x400\n Call Trace:\n  \u003cTASK\u003e\n  genl_family_rcv_msg_doit (net/netlink/genetlink.c:1116)\n  genl_rcv_msg (net/netlink/genetlink.c:1194)\n  netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n  genl_rcv (net/netlink/genetlink.c:1219)\n  netlink_unicast (net/netlink/af_netlink.c:1344)\n  netlink_sendmsg (net/netlink/af_netlink.c:1894)\n  __sys_sendto (net/socket.c:2206)\n  __x64_sys_sendto (net/socket.c:2209)\n  do_syscall_64 (arch/x86/entry/syscall_64.c:63)\n  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n  \u003c/TASK\u003e\n Kernel panic - not syncing: Fatal exception\n\nReject attempts to set more PIDs than nr_cpu_ids in\novs_vport_set_upcall_portids(), and pre-compute the worst-case reply\nsize in ovs_vport_cmd_msg_size() based on that bound, similar to the\nexisting ovs_dp_cmd_msg_size().  nr_cpu_ids matches the cap already\nused by the per-CPU dispatch configuration on the datapath side\n(ovs_dp_cmd_fill_info() serialises at most nr_cpu_ids PIDs), so the\ntwo sides stay consistent."
    }
  ],
  "id": "CVE-2026-45840",
  "lastModified": "2026-06-26T18:56:58.617",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-05-27T11:16:23.363",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/1d6c02b86329883aa467a3a61f8d34369db73a2f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/2091c6aa0df6aba47deb5c8ab232b1cb60af3519"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/8d59b80e69dddb665eb2de36e62859ab2073470e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/b39f763d720d623218bc1d95ace6855d7b474e81"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/d9e47e29aacb9f8a9d59feb6ab5b128a9bbb40b0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/f99ac36b5d7c719d08a69fcdecce40f78a874e15"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/f9ef3db77a383d66847fd082c2b437d8ae4d9c63"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/fa6e90bc443bed8dc0d55bc5ea5b27ffdfe37704"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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