{
  "threat_severity" : "Moderate",
  "public_date" : "2026-03-26T10:22:49Z",
  "bugzilla" : {
    "description" : "Linux kernel: nfnetlink_osf: Linux kernel: Denial of Service in nfnetlink_osf via crafted network packets",
    "id" : "2451664",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2451664"
  },
  "cvss3" : {
    "cvss3_base_score" : "4.4",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H",
    "status" : "draft"
  },
  "cwe" : "CWE-130",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nnfnetlink_osf: validate individual option lengths in fingerprints\nnfnl_osf_add_callback() validates opt_num bounds and string\nNUL-termination but does not check individual option length fields.\nA zero-length option causes nf_osf_match_one() to enter the option\nmatching loop even when foptsize sums to zero, which matches packets\nwith no TCP options where ctx->optp is NULL:\nOops: general protection fault\nKASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\nRIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)\nCall Trace:\nnf_osf_match (net/netfilter/nfnetlink_osf.c:227)\nxt_osf_match_packet (net/netfilter/xt_osf.c:32)\nipt_do_table (net/ipv4/netfilter/ip_tables.c:293)\nnf_hook_slow (net/netfilter/core.c:623)\nip_local_deliver (net/ipv4/ip_input.c:262)\nip_rcv (net/ipv4/ip_input.c:573)\nAdditionally, an MSS option (kind=2) with length < 4 causes\nout-of-bounds reads when nf_osf_match_one() unconditionally accesses\noptp[2] and optp[3] for MSS value extraction.  While RFC 9293\nsection 3.2 specifies that the MSS option is always exactly 4\nbytes (Kind=2, Length=4), the check uses \"< 4\" rather than\n\"!= 4\" because lengths greater than 4 do not cause memory\nsafety issues -- the buffer is guaranteed to be at least\nfoptsize bytes by the ctx->optsize == foptsize check.\nReject fingerprints where any option has zero length, or where an MSS\noption has length less than 4, at add time rather than trusting these\nvalues in the packet matching hot path.", "A flaw was found in the nfnetlink_osf module of the Linux kernel. A remote attacker could send specially crafted network packets containing malformed options, such as zero-length options or a Maximum Segment Size (MSS) option with an invalid length. This could lead to a system crash, resulting in a Denial of Service (DoS), which makes the system unavailable to legitimate users." ],
  "statement" : "Exploitation of this vulnerability requires CAP_NET_ADMIN privileges to load the malicious OS fingerprint via nfnl_osf_add_callback(). Network packets then trigger the crash during fingerprint matching. Since setting up the vulnerable condition requires elevated privileges, and the impact is limited to denial of service, the risk is reduced compared to a purely remote attack.",
  "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" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "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-2026-23397\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-23397\nhttps://lore.kernel.org/linux-cve-announce/2026032634-CVE-2026-23397-d4f0@gregkh/T" ],
  "name" : "CVE-2026-23397",
  "mitigation" : {
    "value" : "To mitigate this issue, prevent the nfnetlink_osf and xt_osf modules from being loaded. See https://access.redhat.com/solutions/41278 for instructions.",
    "lang" : "en:us"
  },
  "csaw" : false
}