Linux Kernel TCP stack Vulnerability Rated 7.5 CVSS

Last refreshed2026-10-15

Status: UPDATED | Advisory ID: CVE-2026-53183

Key Details

CVE	CVE-2026-53183
CVSS Score / Version	7.5 (High) / CVSS v3.1
Updated	2026-10-15
CVSS Vector	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`
CVSS Prose	attack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is unchanged; confidentiality impact is none; integrity impact is none; availability impact is high.
Affected products	Linux Kernel and Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Exploitation prediction (EPSS)	0.49% probability of exploitation in the next 30 days (41% percentile) -- FIRST.org's EPSS model.

Vendor	Product	Affected Versions	Patch Status
Linux	Linux Kernel
Siemens	SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Vendor

Product

Affected Versions

Patch Status

Linux

Linux Kernel

Siemens

SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Subsystems	Controllers & Field I/O, OT Supporting Infrastructure
Sectors	All Sectors

In the Linux kernel, the following vulnerability has been resolved:

mptcp: allow subflow rcv wnd to shrink

In MPTCP connection, the `window` field in the TCP header refers to the

MPTCP-level rcv_nxt and it's right edge should not move backward. Such

constraint is enforced at DSS option generation time.

At the same time, the TCP stack ensures independently that the TCP-level

rcv wnd right's edge does not move backward. That in turn causes artificial

inflating of the MPTCP rcv window when the incoming data is acked at the

TCP level and is OoO in the MPTCP sequence space (or lands in the backlog).

As a consequence, the incoming traffic can exceed the receiver rcvbuf size

even when the sender is not misbehaving.

Prevent such scenario forcibly allowing the TCP subflow to shrink the

TCP-level rcv wnd regardless of the current netns setting. (NVD)

Monitor Linux's and Siemens's web pages for any future patch releases.

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-53183
CVE	https://www.cve.org/CVERecord?id=CVE-2026-53183

Source

Reference

NVD

CVE