CVE-2026-64422

High

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.

Package Linux Kernel
Published 2026-07-25
Last modified 2026-09-08
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.1

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Weakness type

CWE-190

CVE-2026-64422 is a Integer Overflow vulnerability

What is Integer Overflow?

The product performs a calculation that can produce an integer overflow, leading to unexpected values. Learn more on MITRE CWE

Affected versions

Linux kernel versions 2.6.24 and later are affected. Fixed in 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4, 7.2 and their respective stable series.

Affected from
≥ 2.6.24
Fixed in
✓ 5.10.261 5.10.x ✓ 5.15.212 5.15.x ✓ 6.1.178 6.1.x ✓ 6.6.145 6.6.x ✓ 6.12.96 6.12.x ✓ 6.18.39 6.18.x ✓ 7.1.4 7.1.x ✓ 7.2

References

9 total
Showing 5 of 9 references View all on NVD

Frequently asked questions

  • What is CVE-2026-64422?

    CVE-2026-64422 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10 , classified as an Integer Overflow flaw (CWE-190) . It affects Linux kernel versions from 2.6.24 onward and has been patched in 5.10.261, 5.15.212, 6.1.178 and others. CVE-2026-64422 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-64422?

    CVE-2026-64422 has a CVSS score of 7.1 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H .

  • Is there a patch available for CVE-2026-64422?

    Yes. CVE-2026-64422 has been patched. Fixed versions include 5.10.261, 5.15.212, 6.1.178 and others. If you are running Linux kernel 2.6.24 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-64422 actively exploited?

    No. CVE-2026-64422 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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