[AutoPR- Security] Patch flannel for CVE-2026-73500 [HIGH]

[Azure Linux Security Servicing Account (azurelinux-security)]

Auto Patch flannel for CVE-2026-73500.

Autosec pipeline run -> https://dev.azure.com/mariner-org/mariner/_build/results?buildId=1183000&view=results

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• The toolchain has been rebuilt successfully (or no changes were made to it)
• The toolchain/worker package manifests are up-to-date
• Any updated packages successfully build (or no packages were changed)
• Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• All package sources are available
• cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• LICENSE-MAP files are up-to-date (./LICENSES-AND-NOTICES/SPECS/data/licenses.json, ./LICENSES-AND-NOTICES/SPECS/LICENSES-MAP.md, ./LICENSES-AND-NOTICES/SPECS/LICENSE-EXCEPTIONS.PHOTON)
• All source files have up-to-date hashes in the *.signatures.json files
• sudo make go-tidy-all and sudo make go-test-coverage pass
• Documentation has been updated to match any changes to the build system
• Ready to merge

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Summary

What does the PR accomplish, why was it needed?

• Auto Patch flannel for CVE-2026-73500 (HIGH).

Change Log

• CVE-2026-73500

Does this affect the toolchain?

YES/NO

Associated issues

• N/A

Links to CVEs

• https://nvd.nist.gov/vuln/detail/CVE-2026-73500

Test Methodology

• Pipeline build id: Buddy Build URL

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.

[Kanishk Bansal (Kanishk-Bansal)]

/azurepipelines run

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).
1 pipeline(s) were filtered out due to trigger conditions.

[Kanishk Bansal (Kanishk-Bansal)]

Patch Analysis (Matches Upstream)

• Buddy Build fails due to some toolchain error, but package builds fine in CI
• patch applied during the build (check rpm.log)
• patch include an upstream reference
• PR has security tag

[azurelinux-ci-jwt-app]

Auto cherry-pick results:

• 3.0-dev ❌ -> [AUTO-CHERRYPICK] [AutoPR- Security] Patch flannel for CVE-2026-73500 [HIGH] - branch 3.0-dev #18493
  -> Failed. Please see the logs for more information

Auto cherry-pick pipeline run -> https://dev.azure.com/mariner-org/mariner/_build/results?buildId=1184736&view=results