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VulnerabilityPublished Updated

CVE-2026-64422: Linux kernel · Integer Overflow

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.1 High · fixed in f0d88a4cd03affff6c08adf6c63964e235aede43 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score
7.1High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in f0d88a4cd03affff6c08adf6c63964e235aede43, efb8763d7bbb40cff4cc55a6b62c3095a038149c, e81f805824a8109504fce090641b17d135b48cd1 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf, < f0d88a4cd03affff6c08adf6c63964e235aede43
Fixed in
  • f0d88a4cd03affff6c08adf6c63964e235aede43
LinuxLinuxAffected
  • ≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf, < efb8763d7bbb40cff4cc55a6b62c3095a038149c
Fixed in
  • efb8763d7bbb40cff4cc55a6b62c3095a038149c
LinuxLinuxAffected
  • ≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf, < e81f805824a8109504fce090641b17d135b48cd1
Fixed in
  • e81f805824a8109504fce090641b17d135b48cd1
LinuxLinuxAffected
  • ≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf, < bbae351c0f32f7c200249e4aa6561b2b419dcf69
Fixed in
  • bbae351c0f32f7c200249e4aa6561b2b419dcf69
LinuxLinuxAffected
  • ≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf, < a094ac95d3b69adfa1676eb9c8eae6835d4f1671
Fixed in
  • a094ac95d3b69adfa1676eb9c8eae6835d4f1671
LinuxLinuxAffected
  • ≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf, < 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae
Fixed in
  • 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae

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.

References

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