{
  "threat_severity" : "Moderate",
  "public_date" : "2026-04-03T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN",
    "id" : "2454862",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2454862"
  },
  "cvss3" : {
    "cvss3_base_score" : "5.5",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
    "status" : "draft"
  },
  "cwe" : "CWE-474",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nserial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN\nuart_write_room() and uart_write() behave inconsistently when\nxmit_buf is NULL (which happens for PORT_UNKNOWN ports that were\nnever properly initialized):\n- uart_write_room() returns kfifo_avail() which can be > 0\n- uart_write() checks xmit_buf and returns 0 if NULL\nThis inconsistency causes an infinite loop in drivers that rely on\ntty_write_room() to determine if they can write:\nwhile (tty_write_room(tty) > 0) {\nwritten = tty->ops->write(...);\n// written is always 0, loop never exits\n}\nFor example, caif_serial's handle_tx() enters an infinite loop when\nused with PORT_UNKNOWN serial ports, causing system hangs.\nFix by making uart_write_room() also check xmit_buf and return 0 if\nit's NULL, consistent with uart_write().\nReproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13", "A flaw was found in the Linux kernel's serial core component. An inconsistency between the `uart_write_room()` and `uart_write()` functions, specifically when handling `PORT_UNKNOWN` serial ports with a NULL transmit buffer, can lead to an infinite loop. This allows a local user or process to trigger a system hang, resulting in a Denial of Service (DoS)." ],
  "statement" : "The fix aligns `uart_write_room()` with `uart_write()` when no transmit buffer exists. Exploitation requires a path that opens such a port and exercises the buggy loop; impact is a local or subsystem hang, not remote code execution by itself.",
  "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" : "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-2026-23472\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-23472\nhttps://lore.kernel.org/linux-cve-announce/2026040322-CVE-2026-23472-c68c@gregkh/T" ],
  "name" : "CVE-2026-23472",
  "csaw" : false
}