Improper access control in Linux kernel - CVE-2026-31668
Published: April 25, 2026
Vulnerability identifier: #VU127730
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-31668
CWE-ID: CWE-284
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to bypass routing policy restrictions.
The vulnerability exists due to improper access control in the seg6 lwtunnel dst_cache handling when processing input and output paths in different routing contexts. A local user can trigger packet processing through one path so that the other path reuses an incorrect cached destination to bypass routing policy restrictions.
The issue occurs because a single destination cache is shared between seg6_input_core() and seg6_output_core(), even though these paths may perform SID lookup under different routing contexts such as ingress-interface-based rules or VRF table separation.
How to mitigate CVE-2026-31668
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/17d87d42874f5d6c1a0ccc6d9190dfe82a9a7a6a
- https://git.kernel.org/stable/c/1dec91d3b1cefb82635761b7812154af3ef46449
- https://git.kernel.org/stable/c/57d0374d14fa667dec6952173b93e7e84486d5c9
- https://git.kernel.org/stable/c/6305ad032b03d2ea4181b953a66e19a9a6ed053c
- https://git.kernel.org/stable/c/750569d6987a0ff46317a4b86eb3907e296287bf
- https://git.kernel.org/stable/c/84d458018b147176b259347103fccb7e93abd2b1
- https://git.kernel.org/stable/c/c3812651b522fe8437ebb7063b75ddb95b571643
- https://git.kernel.org/stable/c/fb56de5d99218de49d5d43ef3a99e062ecd0f9a1