Nuclio: Unsanitized cron trigger event headers/body injected into CronJob shell command leads to persistent RCE

Exploitation

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

CVSS

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

EPSS

• CVE-2026-52831: 0.53% estimated exploitation activity in the next 30 days; percentile 45.16 (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 Nuclio controller builds a curl invocation string for each cron trigger and stores it as the args of a Kubernetes CronJob container (/bin/sh, -c, <command). Two fields in the trigger specification flow into this string without adequate sanitization: - event.headers keys — interpolated verbatim inside double-quoted --header arguments (lazy.go:2150); any key containing " breaks the quoting context. - event.body — processed with strconv.Quote, which escapes " and \ but not $(), allowing command substitution (lazy.go:2188). Both paths were dynamically verified on Nuclio 1.15.27 (latest as of 2026-05-17). - CVSS 3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H — 9.9 (Critical) - CWE: CWE-78 (Improper Neutralization of Special Elements used in an OS Command) - Affected versions: Nuclio <= 1.15.27 (latest, dynamically verified) --- Details Root Cause When a NuclioFunction with a cron trigger is reconciled by the controller, it calls generateCronTriggerCronJobSpec in…

Published by the source

8 Jul 2026, 20:24 UTC

Last modified by the source

8 Jul 2026, 20:24 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-v5px-423j-pf7p

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# Patch Next advisory brief: CVE-2026-52831

Advisory: Nuclio: Unsanitized cron trigger event headers/body injected into CronJob shell command leads to persistent RCE
IDs: CVE-2026-52831, GHSA-v5px-423j-pf7p
Record: https://patchnext.com/advisories/cve-2026-52831 (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: Critical (CVSS 10.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/nuclio/nuclio 0.0.0-20260601075854-3356b86a8bfa. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/nuclio/nuclio: affected < 0.0.0-20260601075854-3356b86a8bfa; fixed in 0.0.0-20260601075854-3356b86a8bfa

## Suggested inspection (read-only)
- Go github.com/nuclio/nuclio: 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/nuclio/nuclio.
- 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-v5px-423j-pf7p (GitHub-reviewed advisory GHSA-v5px-423j-pf7p lists affected ranges: Go github.com/nuclio/nuclio >=0 <0.0.0-20260601075854-3356b86a8bfa)

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