GHSA-GWMG-Q555-3325
Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-09-08 09:35In the Linux kernel, the following vulnerability has been resolved:
net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes
Reject invalid net.ipv4.tcp_reordering values before they reach TCP
socket state. The sysctl is stored as an int but copied into the
u32 tp->reordering field for new sockets, so negative writes wrap
to large values.
With tcp_mtu_probing=2, the wrapped value can overflow the
tcp_mtu_probe() size calculation and drive the MTU probing path into
an out-of-bounds read. Route tcp_reordering writes through
proc_dointvec_minmax() and require it to be at least 1. Also require
tcp_max_reordering to be at least 1 so the configured maximum cannot
become negative either.
When registering the table for a non-init network namespace, relocate
extra2 pointers that refer into init_net.ipv4 so the
tcp_reordering upper bound follows that namespace's
tcp_max_reordering.
Harden tcp_mtu_probe() itself by computing size_needed as u64.
This keeps the send queue and window checks from being bypassed through
signed integer overflow.
{
"affected": [],
"aliases": [
"CVE-2026-64422"
],
"database_specific": {
"cwe_ids": [
"CWE-190"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-25T10:17:26Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv4: bound TCP reordering sysctl writes and MTU probe sizes\n\nReject invalid `net.ipv4.tcp_reordering` values before they reach TCP\nsocket state. The sysctl is stored as an `int` but copied into the\n`u32` `tp-\u003ereordering` field for new sockets, so negative writes wrap\nto large values.\n\nWith `tcp_mtu_probing=2`, the wrapped value can overflow the\n`tcp_mtu_probe()` size calculation and drive the MTU probing path into\nan out-of-bounds read. Route `tcp_reordering` writes through\n`proc_dointvec_minmax()` and require it to be at least 1. Also require\n`tcp_max_reordering` to be at least 1 so the configured maximum cannot\nbecome negative either.\n\nWhen registering the table for a non-init network namespace, relocate\n`extra2` pointers that refer into `init_net.ipv4` so the\n`tcp_reordering` upper bound follows that namespace\u0027s\n`tcp_max_reordering`.\n\nHarden `tcp_mtu_probe()` itself by computing `size_needed` as `u64`.\nThis keeps the send queue and window checks from being bypassed through\nsigned integer overflow.",
"id": "GHSA-gwmg-q555-3325",
"modified": "2026-09-08T09:35:36Z",
"published": "2026-07-25T12:31:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64422"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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