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Review reviewHigh

CVE-2026-64422

Linux

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...

CVSS
7.1
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.25
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.1

Vulnerability overview

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...

Affected product and versions

Product
Linux
Affected versions
>= 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf < f0d88a4cd03affff6c08adf6c63964e235aede43, >= 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf < 27ddf4486c7dbf5bdd393fa8bef6b67179796d98, >= 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf < 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae, >= 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf < e81f805824a8109504fce090641b17d135b48cd1, >= 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf < 99206ce2244f8a3ed64298d0667c9055845a5dc7, >= 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf < bbae351c0f32f7c200249e4aa6561b2b419dcf69, >= 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf < a094ac95d3b69adfa1676eb9c8eae6835d4f1671, >= 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf < efb8763d7bbb40cff4cc55a6b62c3095a038149c, >= 2.6.24
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
CWE
Not available
CVE-2026-64422 — Linux | SECUFOCUS NOW