CVE-2026-31668Network attack vector

Routing-policy bypass via cross-context SID cache reuse

Published Apr 24, 2026 · Updated Apr 24, 2026

Routing-policy bypass in the Linux kernel allows remote attackers to reuse a cached SID route from the wrong routing context. seg6_input_core() and seg6_output_core() share one dst_cache, so the path running second blindly accepts a post-encapsulation lookup performed under different interface or VRF rules. Exposure requires a seg6 lwtunnel route used by both paths in distinct routing contexts, and packets can bypass the routing policy applicable to the second path.

CVSS severity9.8
Critical
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Routing-policy bypass in the Linux kernel allows remote attackers to reuse a cached SID route from the wrong routing context. seg6_input_core() and seg6_output_core() share one dst_cache, so the path running second blindly accepts a post-encapsulation lookup performed under different interface or VRF rules. Exposure requires a seg6 lwtunnel route used by both paths in distinct routing contexts, and packets can bypass the routing policy applicable to the second path.

The record

CVE
CVE-2026-31668
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.10
  2. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <17d87d42874f5d6c1a0ccc6d9190dfe82a9a7a6a
  3. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <1dec91d3b1cefb82635761b7812154af3ef46449
  4. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <57d0374d14fa667dec6952173b93e7e84486d5c9
  5. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <6305ad032b03d2ea4181b953a66e19a9a6ed053c
  6. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <750569d6987a0ff46317a4b86eb3907e296287bf
  7. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <84d458018b147176b259347103fccb7e93abd2b1
  8. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <c3812651b522fe8437ebb7063b75ddb95b571643
  9. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <fb56de5d99218de49d5d43ef3a99e062ecd0f9a1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4.10; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <17d87d42874f5d6c1a0ccc6d9190dfe82a9a7a6a; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <1dec91d3b1cefb82635761b7812154af3ef46449; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <57d0374d14fa667dec6952173b93e7e84486d5c9; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <6305ad032b03d2ea4181b953a66e19a9a6ed053c; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <750569d6987a0ff46317a4b86eb3907e296287bf; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <84d458018b147176b259347103fccb7e93abd2b1; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <c3812651b522fe8437ebb7063b75ddb95b571643; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <fb56de5d99218de49d5d43ef3a99e062ecd0f9a1

Published CVSS scores

3.3OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

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