CVE-2026-31668

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux6c8702c60b88651072460f3f4026c7dfe2521d12 < 1dec91d3b1cefb82635761b7812154af3ef46449affected
LinuxLinux6c8702c60b88651072460f3f4026c7dfe2521d12 < 750569d6987a0ff46317a4b86eb3907e296287bfaffected
LinuxLinux6c8702c60b88651072460f3f4026c7dfe2521d12 < 57d0374d14fa667dec6952173b93e7e84486d5c9affected
LinuxLinux6c8702c60b88651072460f3f4026c7dfe2521d12 < 84d458018b147176b259347103fccb7e93abd2b1affected
LinuxLinux6c8702c60b88651072460f3f4026c7dfe2521d12 < 6305ad032b03d2ea4181b953a66e19a9a6ed053caffected
LinuxLinux6c8702c60b88651072460f3f4026c7dfe2521d12 < fb56de5d99218de49d5d43ef3a99e062ecd0f9a1affected
LinuxLinux6c8702c60b88651072460f3f4026c7dfe2521d12 < 17d87d42874f5d6c1a0ccc6d9190dfe82a9a7a6aaffected
LinuxLinux6c8702c60b88651072460f3f4026c7dfe2521d12 < c3812651b522fe8437ebb7063b75ddb95b571643affected
LinuxLinux4.10affected
LinuxLinux0 < 4.10unaffected
LinuxLinux5.10.253 <= 5.10.*unaffected
LinuxLinux5.15.203 <= 5.15.*unaffected
LinuxLinux6.1.169 <= 6.1.*unaffected
LinuxLinux6.6.135 <= 6.6.*unaffected
LinuxLinux6.12.82 <= 6.12.*unaffected
LinuxLinux6.18.23 <= 6.18.*unaffected
LinuxLinux6.19.13 <= 6.19.*unaffected
LinuxLinux7.0 <= *unaffected

Weaknesses

References