CVE-2026-64422net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In 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.
- CVSS
- 7.1 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf before f0d88a4cd03affff6c08adf6c63964e235aede43; 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf builds before 27ddf4486c7dbf5bdd393fa8bef6b67179796d98; from 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf before 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae; from 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf before e81f805824a8109504fce090641b17d135b48cd1; from 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf before 99206ce2244f8a3ed64298d0667c9055845a5dc7; from 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf before bbae351c0f32f7c200249e4aa6561b2b419dcf69; from 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf before a094ac95d3b69adfa1676eb9c8eae6835d4f1671; from 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf before efb8763d7bbb40cff4cc55a6b62c3095a038149c | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 2.6.24.1 before 5.10.261; from 5.11 before 5.15.212; from 5.16 before 6.1.178; from 6.2 before 6.6.145; from 6.7 before 6.12.96; from 6.13 before 6.18.39; from 6.19 before 7.1.4; 2.6.24; and 5 more ranges | NVD |
References
- https://git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43patch
- https://git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98patch
- https://git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efaepatch
- https://git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1patch
- https://git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7patch
- https://git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69patch
- https://git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671patch
- https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149cpatch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.