NetBox up to 4.5.4 RenderTemplateMixin.get_environment_params finalize permissive list of allowed inputs

Summaryinfo

A vulnerability labeled as critical has been found in NetBox up to 4.5.4. Affected is the function RenderTemplateMixin.get_environment_params. Such manipulation of the argument finalize leads to permissive list of allowed inputs. This vulnerability is documented as CVE-2026-29514. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in NetBox up to 4.5.4 and classified as critical. Affected by this issue is the function RenderTemplateMixin.get_environment_params. The manipulation of the argument finalize with an unknown input leads to a permissive list of allowed inputs vulnerability. Using CWE to declare the problem leads to CWE-183. The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are explicitly allowed by policy because the inputs are assumed to be safe, but the list is too permissive - that is, it allows an input that is unsafe, leading to resultant weaknesses. Impacted is confidentiality, integrity, and availability. CVE summarizes:

NetBox versions 4.3.5 through 4.5.4 contain a remote code execution vulnerability in the RenderTemplateMixin.get_environment_params() method that allows authenticated users with exporttemplate or configtemplate permissions to execute arbitrary code by specifying malicious Python callables in the environment_params field. Attackers can bypass Jinja2 SandboxedEnvironment protections by setting the finalize parameter to any importable Python callable such as subprocess.getoutput, which is invoked on every rendered expression outside the sandbox's call interception mechanism, achieving remote code execution as the NetBox service user.

The weakness was released by Valentin Lobstein. The advisory is available at chocapikk.com. This vulnerability is handled as CVE-2026-29514 since 03/04/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 05/05/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at EUVD (EUVD-2026-26997) and CERT Bund (WID-SEC-2026-1355). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Open Source NetBox

Productinfo

Name

• NetBox

Version

• 4.5.0
• 4.5.1
• 4.5.2
• 4.5.3
• 4.5.4

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion