CVE-2026-31668

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

State: Published
Severity: 9.8 Critical
Published: Apr 24, 2026
Updated: Oct 19, 2026
Reserved: Mar 9, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

CWE-459 Incomplete Cleanup

Affected Products

Product	Versions
LinuxLinux	6c8702c60b88651072460f3f4026c7dfe2521d12 to before 1dec91d3b1cefb82635761b7812154af3ef46449Affected 6c8702c60b88651072460f3f4026c7dfe2521d12 to before 750569d6987a0ff46317a4b86eb3907e296287bfAffected 6c8702c60b88651072460f3f4026c7dfe2521d12 to before 57d0374d14fa667dec6952173b93e7e84486d5c9Affected 6c8702c60b88651072460f3f4026c7dfe2521d12 to before 84d458018b147176b259347103fccb7e93abd2b1Affected 6c8702c60b88651072460f3f4026c7dfe2521d12 to before 6305ad032b03d2ea4181b953a66e19a9a6ed053cAffected 6c8702c60b88651072460f3f4026c7dfe2521d12 to before fb56de5d99218de49d5d43ef3a99e062ecd0f9a1Affected 6c8702c60b88651072460f3f4026c7dfe2521d12 to before 17d87d42874f5d6c1a0ccc6d9190dfe82a9a7a6aAffected 6c8702c60b88651072460f3f4026c7dfe2521d12 to before c3812651b522fe8437ebb7063b75ddb95b571643Affected
LinuxLinux	4.10Affected before 4.10Not affected 5.10.253 through 5.10.Not affected 5.15.203 through 5.15.Not affected 6.1.169 through 6.1.Not affected 6.6.135 through 6.6.Not affected 6.12.82 through 6.12.Not affected 6.18.23 through 6.18.Not affected 6.19.13 through 6.19.*Not affected 7.0 and laterNot affected

Product

Versions

LinuxLinux

6c8702c60b88651072460f3f4026c7dfe2521d12 to before 1dec91d3b1cefb82635761b7812154af3ef46449Affected
6c8702c60b88651072460f3f4026c7dfe2521d12 to before 750569d6987a0ff46317a4b86eb3907e296287bfAffected
6c8702c60b88651072460f3f4026c7dfe2521d12 to before 57d0374d14fa667dec6952173b93e7e84486d5c9Affected
6c8702c60b88651072460f3f4026c7dfe2521d12 to before 84d458018b147176b259347103fccb7e93abd2b1Affected
6c8702c60b88651072460f3f4026c7dfe2521d12 to before 6305ad032b03d2ea4181b953a66e19a9a6ed053cAffected
6c8702c60b88651072460f3f4026c7dfe2521d12 to before fb56de5d99218de49d5d43ef3a99e062ecd0f9a1Affected
6c8702c60b88651072460f3f4026c7dfe2521d12 to before 17d87d42874f5d6c1a0ccc6d9190dfe82a9a7a6aAffected
6c8702c60b88651072460f3f4026c7dfe2521d12 to before c3812651b522fe8437ebb7063b75ddb95b571643Affected

LinuxLinux

4.10Affected
before 4.10Not affected
5.10.253 through 5.10.*Not affected
5.15.203 through 5.15.*Not affected
6.1.169 through 6.1.*Not affected
6.6.135 through 6.6.*Not affected
6.12.82 through 6.12.*Not affected
6.18.23 through 6.18.*Not affected
6.19.13 through 6.19.*Not affected
7.0 and laterNot affected

References

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