Fission builder pods auto-mount the fission-builder ServiceAccount token in the user-supplied builder container

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.9 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-50565: 0.26% estimated exploitation activity in the next 30 days; percentile 17.23 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Fission builder pods were created with ServiceAccountName: fission-builder and no AutomountServiceAccountToken: false, so the kubelet auto-mounted the service-account token into every container in the pod — including the user-supplied builder image. Details The user controls the builder container image, command, and podspec through Environment.spec.builder.image / .container / .podspec. With the SA token auto-mounted at /var/run/secrets/kubernetes.io/serviceaccount/token inside that container, any code running there inherited the fission-builder identity. The fission-builder SA holds namespace-wide get on secrets and configmaps (pkg/utils/serviceaccount.go), so the user-controlled builder container could read every Secret in the builder namespace by name. This is the buildermgr sibling of GHSA-85g2-pmrx-r49q (CVE-2026-46617), whose fix suppressed the SA-token automount on function runtime pods but did not cover the structurally identical primitive in…

Published by the source

30 Jun 2026, 18:20 UTC

Last modified by the source

30 Jun 2026, 18:20 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-8wcj-mfrc-jx5q

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# Patch Next advisory brief: CVE-2026-50565

Advisory: Fission builder pods auto-mount the fission-builder ServiceAccount token in the user-supplied builder container
IDs: CVE-2026-50565, GHSA-8wcj-mfrc-jx5q
Record: https://patchnext.com/advisories/cve-2026-50565 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/fission/fission 1.24.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/fission/fission: affected <= 1.23.0; fixed in 1.24.0

## Suggested inspection (read-only)
- Go github.com/fission/fission: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/fission/fission.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8wcj-mfrc-jx5q (GitHub-reviewed advisory GHSA-8wcj-mfrc-jx5q lists affected ranges: Go github.com/fission/fission >=0 <=1.23.0)

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