High Memory corruption

CVE-2026-64422 — net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes

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.

Published Jul 25, 2026 · Updated Oct 15, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database, GitHub Security Advisories · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.1% (30-day exploitation probability)+0
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.14%

ahead of 3% of scored CVEs · Oct 15, 2026

Affects

Linux

Linux and 1 more

CVSS base

7.1

High · 3 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	version 2.6.24≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf and < efb8763d7bbb40cff4cc55a6b62c3095a038149c≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf and < a094ac95d3b69adfa1676eb9c8eae6835d4f1671≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf and < bbae351c0f32f7c200249e4aa6561b2b419dcf69≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf and < 99206ce2244f8a3ed64298d0667c9055845a5dc7≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf and < e81f805824a8109504fce090641b17d135b48cd1≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf and < 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf and < 27ddf4486c7dbf5bdd393fa8bef6b67179796d98 and 1 more ≥ 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf and < f0d88a4cd03affff6c08adf6c63964e235aede43	Vulnerable	CVE Program (cve.org) e CISA ADP
Linux	Linux Kernel	version 2.6.24-rc7version 2.6.24-rc8≥ 2.6.24.1 and < 5.10.261version 2.6.24-rc6version 2.6.24-rc5version 2.6.24-rc4version 2.6.24≥ 6.19 and < 7.1.4 and 5 more ≥ 6.13 and < 6.18.39≥ 6.7 and < 6.12.96≥ 6.2 and < 6.6.145≥ 5.16 and < 6.1.178≥ 5.11 and < 5.15.212	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.1	CVSS 3.1	High	1.8	5.2	416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
7.1	CVSS 3.1	High	—	—	GitHub, Inc. via GitHub Security Advisories
7.1	CVSS 3.1	High	—	—	Linux via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-190 · Integer Overflow or Wraparound

Other CVEs with this weakness →

EPSS over time FIRST

Oct 14, 2026 → Oct 15, 2026 · 2 reading(s) · max 0.14%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

2026
Fix documented
Oct 15, 2026 · NIST National Vulnerability Database
Affected products added · linux/linux kernel
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · Published → Modified
Oct 15, 2026 · NIST National Vulnerability Database
Record published
Oct 15, 2026
CVSS changed · 7.1
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Published
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record created in this database
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
CVE published
Jul 25, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 15, 2026 – Oct 15, 2026
1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

12 on the record

git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671
Patch, CVE Program (cve.org) e CISA ADP
git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98
Patch, CVE Program (cve.org) e CISA ADP
git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7
Patch, CVE Program (cve.org) e CISA ADP
git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae
Patch, CVE Program (cve.org) e CISA ADP
git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69
Patch, CVE Program (cve.org) e CISA ADP
git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43
Patch, CVE Program (cve.org) e CISA ADP
git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1
Patch, CVE Program (cve.org) e CISA ADP
git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c
Patch, CVE Program (cve.org) e CISA ADP
nvd.nist.gov/vuln/detail/CVE-2026-64422
GitHub Security Advisories
cert-portal.siemens.com/productcert/html/ssa-457936.html
NIST National Vulnerability Database
cert-portal.siemens.com/productcert/html/ssa-019113.html
NIST National Vulnerability Database
github.com/advisories/GHSA-gwmg-q555-3325
GitHub Security Advisories

Elsewhere on this site

Linux
every CVE for this vendor

Memory corruption
same class

CWE-190
other pages naming this weakness

Related CVEs (same products)

Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 16h
Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 16h
Unknown CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
Unknown CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
Unknown CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d
Unknown CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CISA SSVC assessment.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-64422 is "net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.1 describes technical severity. EPSS 0.14% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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