CVE-2026-52833: Nuclio: Unsanitized runtimeAttributes.repositories injected into Groovy build.gradle leads to build-time RCE

Nuclio’s Java runtime generates a build.gradle file during function builds using Go’s text/template package. The template renders runtimeAttributes.repositories[] values with the {{ . }} action, which performs no escaping. An attacker can embed a closing brace (}) to break out of the repositories {} block and append arbitrary Groovy statements that execute unconditionally during the Gradle configuration phase.

The Dashboard API runs with NOP authentication by default, so no credentials are required. The build container runs as root. The injected command output confirmed by dynamic testing:

[RCE-PROOF] uid=0(root) gid=0(root) groups=0(root)
nuclio-kanikojob.nuclioprocessorvul006rcev3latest.tkxsslz06ppcr
root
BUILD SUCCESSFUL in 512ms

• CWE: CWE-94 (Improper Control of Generation of Code / Code Injection)
• Affected versions: Nuclio <= 1.15.27 (latest as of 2026-05-17, dynamically verified)