CVE-2026-64422
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.13%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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 3.1
- 7.1 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- EPSS
- 0.13% probability · 3th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-190
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98Patch
- https://git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efaePatch
- https://git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7Patch
- https://git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671Patch
- https://git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69Patch
- https://git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1Patch
- https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149cPatch
- https://git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43Patch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.