Unauthenticated Remote Vulnerability in Linux Linux Kernel Rates 9.8 CVSS

Last refreshed2026-10-15

Status: UPDATED | Advisory ID: CVE-2026-53221

Key Details

CVE	CVE-2026-53221
CVSS Score / Version	9.8 (Critical) / CVSS v3.1
Updated	2026-10-15
CVSS Vector	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 high; integrity impact is high; availability impact is high.
Affected products	Linux Kernel and Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Exploitation prediction (EPSS)	0.58% probability of exploitation in the next 30 days (46% 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:

ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()

In vti6_tnl_lookup(), when an exact match for a tunnel fails,

the code falls back to searching for wildcard tunnels:

- Tunnels matching the packet's local address, with any remote address

wildcard remote).

- Tunnels matching the packet's remote address, with any local address

(wildcard local).

However, vti6 stores all these different types of tunnels in the same

hash table (ip6n->tnls_r_l) prone to hash collisions.

The bug is that the fallback search loops in vti6_tnl_lookup() were

missing checks to ensure that the candidate tunnel actually has

a wildcard address. (NVD)

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

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-53221
CVE	https://www.cve.org/CVERecord?id=CVE-2026-53221

Source

Reference

NVD

CVE