{
  "threat_severity" : "Moderate",
  "public_date" : "2026-04-13T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp",
    "id" : "2457842",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2457842"
  },
  "cvss3" : {
    "cvss3_base_score" : "5.8",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H",
    "status" : "draft"
  },
  "cwe" : "CWE-824",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nnetfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp\nprocess_sdp() declares union nf_inet_addr rtp_addr on the stack and\npasses it to the nf_nat_sip sdp_session hook after walking the SDP\nmedia descriptions. However rtp_addr is only initialized inside the\nmedia loop when a recognized media type with a non-zero port is found.\nIf the SDP body contains no m= lines, only inactive media sections\n(m=audio 0 ...) or only unrecognized media types, rtp_addr is never\nassigned. Despite that, the function still calls hooks->sdp_session()\nwith &rtp_addr, causing nf_nat_sdp_session() to format the stale stack\nvalue as an IP address and rewrite the SDP session owner and connection\nlines with it.\nWith CONFIG_INIT_STACK_ALL_ZERO (default on most distributions) this\nresults in the session-level o= and c= addresses being rewritten to\n0.0.0.0 for inactive SDP sessions. Without stack auto-init the\nrewritten address is whatever happened to be on the stack.\nFix this by pre-initializing rtp_addr from the session-level connection\naddress (caddr) when available, and tracking via a have_rtp_addr flag\nwhether any valid address was established. Skip the sdp_session hook\nentirely when no valid address exists.", "A flaw was found in the Linux kernel's netfilter subsystem, specifically within the nf_conntrack_sip module. This vulnerability occurs in the process_sdp function when the rtp_addr variable is used without proper initialization if the Session Description Protocol (SDP) body lacks recognized media types or active media sections. A remote attacker could potentially exploit this by sending specially crafted SDP messages, leading to the rewriting of session-level owner and connection addresses with uninitialized or stale stack values. This could result in information disclosure or unexpected network behavior, potentially causing a denial of service." ],
  "statement" : "The bug is confined to SIP sessions handled by the connection-tracking helper and NAT SDP hooks. It requires SIP traffic traversing a host with `nf_conntrack_sip` (and relevant NAT) loaded. Integrity of signaling is affected; remote attackers who can pass SDP through the helper can influence rewritten addresses. Scope should be reviewed against whether IPv4/IPv6 SIP transit applies (network vs. strictly local control plane).",
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "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 8",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  }, {
    "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-2026-31427\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-31427\nhttps://lore.kernel.org/linux-cve-announce/2026041357-CVE-2026-31427-1afe@gregkh/T" ],
  "name" : "CVE-2026-31427",
  "mitigation" : {
    "value" : "To mitigate this issue, prevent the `nf_conntrack_sip` module from being loaded when SIP helper/NAT is not required. See https://access.redhat.com/solutions/41278 for instructions.",
    "lang" : "en:us"
  },
  "csaw" : false
}