CVE-2026-31668 seg6: separate dst_cache for input and output paths in seg6 lwtunnel

What is CVE-2026-31668?

CVE-2026-31668 is a critical vulnerability in Linux kernel, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

seg6: separate dst_cache for input and output paths in seg6 lwtunnel

The seg6 lwtunnel uses a single dst_cache per encap route, shared between seg6_input_core() and seg6_output_core(). These two paths can perform the post-encap SID lookup in different routing contexts (e.g., ip rules matching on the ingress interface, or VRF table separation). Whichever path runs first populates the cache, and the other reuses it blindly, bypassing its own lookup.

Fix this by splitting the cache into cache_input and cache_output, so each path maintains its own cached dst independently.

Weakness: CWE-459

Which versions are affected by CVE-2026-31668?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-31668?

Apply the vendor's patch.

Is CVE-2026-31668 being exploited?

There is no known exploitation of CVE-2026-31668 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-83813, BELL-CVE-2026-31668, DEBIAN-CVE-2026-31668, GHSA-r2p4-96h8-cc74, ROOT-OS-DEBIAN-11-CVE-2026-31668, ROOT-OS-DEBIAN-12-CVE-2026-31668 and 4 more.