{
  "threat_severity" : "Critical",
  "public_date" : "2026-05-01T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: ip6_tunnel: clear skb2->cb[] in ip4ip6_err()",
    "id" : "2464351",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2464351"
  },
  "cvss3" : {
    "cvss3_base_score" : "8.8",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
    "status" : "verified"
  },
  "cwe" : "CWE-843",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nip6_tunnel: clear skb2->cb[] in ip4ip6_err()\nOskar Kjos reported the following problem.\nip4ip6_err() calls icmp_send() on a cloned skb whose cb[] was written\nby the IPv6 receive path as struct inet6_skb_parm. icmp_send() passes\nIPCB(skb2) to __ip_options_echo(), which interprets that cb[] region\nas struct inet_skb_parm (IPv4). The layouts differ: inet6_skb_parm.nhoff\nat offset 14 overlaps inet_skb_parm.opt.rr, producing a non-zero rr\nvalue. __ip_options_echo() then reads optlen from attacker-controlled\npacket data at sptr[rr+1] and copies that many bytes into dopt->__data,\na fixed 40-byte stack buffer (IP_OPTIONS_DATA_FIXED_SIZE).\nTo fix this we clear skb2->cb[], as suggested by Oskar Kjos.\nAlso add minimal IPv4 header validation (version == 4, ihl >= 5).", "A flaw was found in the Linux kernel's IPv6 tunnel implementation. A remote attacker could exploit this flaw by sending malicious ICMPv6 error messages to cause a stack-based buffer overflow in the kernel's IPv4-over-IPv6 tunnel error handling code. This could result in a kernel crash (denial of service) or potentially allow arbitrary code execution with kernel privileges." ],
  "statement" : "This Critical flaw in the Linux kernel's IPv6 tunneling error handling can lead to a stack buffer overflow. An unauthenticated remote attacker could exploit this by sending specially crafted network packets, potentially resulting in a denial of service or information disclosure on affected Red Hat Enterprise Linux systems.",
  "affected_release" : [ {
    "product_name" : "NVIDIA for RHEL 10",
    "release_date" : "2026-06-12T00:00:00Z",
    "advisory" : "RHSA-2026:25534",
    "cpe" : "cpe:/a:redhat:enterprise_linux_nvidia:10::el10",
    "package" : "kernel-0:6.12.0-212.10.el10nv"
  }, {
    "product_name" : "Red Hat Enterprise Linux 10",
    "release_date" : "2026-06-11T00:00:00Z",
    "advisory" : "RHSA-2026:25191",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10.2",
    "package" : "kernel-0:6.12.0-211.22.1.el10_2"
  }, {
    "product_name" : "Red Hat Enterprise Linux 10.0 Extended Update Support",
    "release_date" : "2026-06-08T00:00:00Z",
    "advisory" : "RHSA-2026:24343",
    "cpe" : "cpe:/o:redhat:enterprise_linux_eus:10.0",
    "package" : "kernel-0:6.12.0-55.77.1.el10_0"
  }, {
    "product_name" : "Red Hat Enterprise Linux 6 Extended Lifecycle Support  - EXTENSION",
    "release_date" : "2026-06-22T00:00:00Z",
    "advisory" : "RHSA-2026:27719",
    "cpe" : "cpe:/o:redhat:rhel_els:6",
    "package" : "kernel-0:2.6.32-754.61.1.el6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7 Extended Lifecycle Support",
    "release_date" : "2026-06-22T00:00:00Z",
    "advisory" : "RHSA-2026:27729",
    "cpe" : "cpe:/o:redhat:rhel_els:7",
    "package" : "kernel-0:3.10.0-1160.153.1.el7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "release_date" : "2026-06-10T00:00:00Z",
    "advisory" : "RHSA-2026:25120",
    "cpe" : "cpe:/a:redhat:enterprise_linux:8::nfv",
    "package" : "kernel-rt-0:4.18.0-553.132.1.rt7.473.el8_10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "release_date" : "2026-06-10T00:00:00Z",
    "advisory" : "RHSA-2026:25121",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8",
    "package" : "kernel-0:4.18.0-553.132.1.el8_10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support",
    "release_date" : "2026-06-17T00:00:00Z",
    "advisory" : "RHSA-2026:26535",
    "cpe" : "cpe:/o:redhat:rhel_aus:8.4",
    "package" : "kernel-0:4.18.0-305.194.1.el8_4"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On",
    "release_date" : "2026-06-17T00:00:00Z",
    "advisory" : "RHSA-2026:26535",
    "cpe" : "cpe:/o:redhat:rhel_eus_long_life:8.4",
    "package" : "kernel-0:4.18.0-305.194.1.el8_4"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support",
    "release_date" : "2026-06-12T00:00:00Z",
    "advisory" : "RHSA-2026:25533",
    "cpe" : "cpe:/o:redhat:rhel_aus:8.6",
    "package" : "kernel-0:4.18.0-372.195.1.el8_6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On",
    "release_date" : "2026-06-12T00:00:00Z",
    "advisory" : "RHSA-2026:25533",
    "cpe" : "cpe:/o:redhat:rhel_eus_long_life:8.6",
    "package" : "kernel-0:4.18.0-372.195.1.el8_6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8.8 Telecommunications Update Service",
    "release_date" : "2026-06-04T00:00:00Z",
    "advisory" : "RHSA-2026:22964",
    "cpe" : "cpe:/o:redhat:rhel_tus:8.8",
    "package" : "kernel-0:4.18.0-477.145.1.el8_8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions",
    "release_date" : "2026-06-04T00:00:00Z",
    "advisory" : "RHSA-2026:22964",
    "cpe" : "cpe:/o:redhat:rhel_e4s:8.8",
    "package" : "kernel-0:4.18.0-477.145.1.el8_8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2026-06-11T00:00:00Z",
    "advisory" : "RHSA-2026:25217",
    "cpe" : "cpe:/a:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-687.15.1.el9_8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2026-06-11T00:00:00Z",
    "advisory" : "RHSA-2026:25217",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-687.15.1.el9_8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions",
    "release_date" : "2026-06-03T00:00:00Z",
    "advisory" : "RHSA-2026:22940",
    "cpe" : "cpe:/a:redhat:rhel_e4s:9.2",
    "package" : "kernel-0:5.14.0-284.174.1.el9_2"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions",
    "release_date" : "2026-06-03T00:00:00Z",
    "advisory" : "RHSA-2026:22900",
    "cpe" : "cpe:/a:redhat:rhel_e4s:9.2::nfv",
    "package" : "kernel-rt-0:5.14.0-284.174.1.rt14.459.el9_2"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions",
    "release_date" : "2026-06-04T00:00:00Z",
    "advisory" : "RHSA-2026:23237",
    "cpe" : "cpe:/a:redhat:rhel_e4s:9.4",
    "package" : "kernel-0:5.14.0-427.129.1.el9_4"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9.6 Extended Update Support",
    "release_date" : "2026-06-04T00:00:00Z",
    "advisory" : "RHSA-2026:23224",
    "cpe" : "cpe:/a:redhat:rhel_eus:9.6",
    "package" : "kernel-0:5.14.0-570.119.1.el9_6"
  }, {
    "product_name" : "Red Hat OpenShift Container Platform 4.18",
    "release_date" : "2026-06-17T00:00:00Z",
    "advisory" : "RHSA-2026:25181",
    "cpe" : "cpe:/a:redhat:openshift:4.18::el9",
    "package" : "rhcos-418.94.202606051320-0"
  }, {
    "product_name" : "Red Hat OpenShift Container Platform 4.19",
    "release_date" : "2026-06-17T00:00:00Z",
    "advisory" : "RHSA-2026:25200",
    "cpe" : "cpe:/a:redhat:openshift:4.19::el9",
    "package" : "rhcos-4.19.9.6.202606100451-0"
  }, {
    "product_name" : "Red Hat OpenShift Container Platform 4.20",
    "release_date" : "2026-06-16T00:00:00Z",
    "advisory" : "RHSA-2026:25193",
    "cpe" : "cpe:/a:redhat:openshift:4.20::el9",
    "package" : "rhcos-4.20.9.6.202606101223-0"
  }, {
    "product_name" : "Red Hat OpenShift Container Platform 4.21",
    "release_date" : "2026-06-16T00:00:00Z",
    "advisory" : "RHSA-2026:25186",
    "cpe" : "cpe:/a:redhat:openshift:4.21::el9",
    "package" : "rhcos-4.21.9.6.202606101139-0"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "fix_state" : "Not affected",
    "package_name" : "libkrun",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-43037\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-43037\nhttps://lore.kernel.org/linux-cve-announce/2026050102-CVE-2026-43037-0346@gregkh/T" ],
  "name" : "CVE-2026-43037",
  "mitigation" : {
    "value" : "Mitigation for this issue is to skip loading the affected module `ip6_tunnel` onto the system till we have a fix available, this can be done by a blacklist mechanism, this will ensure the driver is not loaded at the boot time.\n~~~\nHow do I blacklist a kernel module to prevent it from loading automatically? \nhttps://access.redhat.com/solutions/41278  \n~~~\nWe may also want to detection and monitoring an affected system as below:\n~~~\nMonitor for exploitation attempts:\n# Enable kernel audit for IPv6 tunnel operations\nauditctl -a always,exit -F arch=b64 -S socket -F a0=10 -F a1=3 -k ipv6_tunnel\n# Monitor system logs for kernel panics/crashes\njournalctl -k -p err -f | grep -i \"ip6_tunnel\\|icmp\\|stack\"\n~~~",
    "lang" : "en:us"
  },
  "csaw" : false
}