CVE-2023-35926
Insecure sandbox in Backstage Scaffolder plugin
Backstage is an open platform for building developer portals. The Backstage scaffolder-backend plugin uses a templating library that requires sandbox, as it by design allows for code injection. The library used for this sandbox so far has been vm2, but in light of several past vulnerabilities and existing vulnerabilities that may not have a fix, the plugin has switched to using a different sandbox library. A malicious actor with write access to a registered scaffolder template could manipulate the template in a way that allows for remote code execution on the scaffolder-backend instance. This was only exploitable in the template YAML definition itself and not by user input data. This is vulnerability is fixed in version 1.15.0 of @backstage/plugin-scaffolder-backend.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
8.1
Insecure sandbox in Backstage Scaffolder plugin
Backstage is an open platform for building developer portals. The Backstage scaffolder-backend plugin uses a templating library that requires sandbox, as it by design allows for code injection. The library used for this sandbox so far has been vm2, but in light of several past vulnerabilities and existing vulnerabilities that may not have a fix, the plugin has switched to using a different sandbox library. A malicious actor with write access to a registered scaffolder template could manipulate the template in a way that allows for remote code execution on the scaffolder-backend instance. This was only exploitable in the template YAML definition itself and not by user input data. This is vulnerability is fixed in version 1.15.0 of @backstage/plugin-scaffolder-backend.
- Record
CVE-2023-35926- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
EUVDEUVD-2023-1899
8.1
Backstage is an open platform for building developer portals. The Backstage scaffolder-backend plugin uses a templating library that requires sandbox, as it by design allows for code injection. The library used for this sandbox so far has been vm2, but in light of several past vulnerabilities and existing vulnerabilities that may not have a fix, the plugin has switched to using a different sandbox library. A malicious actor with write access to a registered scaffolder template could manipulate the template in a way that allows for remote code execution on the scaffolder-backend instance. This was only exploitable in the template YAML definition itself and not by user input data. This is vulnerability is fixed in version 1.15.0 of @backstage/plugin-scaffolder-backend.
- Record
EUVD-2023-1899- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-wg6p-jmpc-xjmr
8.0
Backstage Scaffolder plugin has insecure sandbox
The Backstage scaffolder-backend plugin uses a templating library that requires a sandbox, as it by design allows for code injection. The library used for this sandbox so far has been vm2, but in light of several past vulnerabilities and existing vulnerabilities that may not have a fix, the plugin has switched to using a different sandbox library.
Impact
A malicious actor with write access to a registered scaffolder template could manipulate the template in a way that allows for remote code execution on the scaffolder-backend instance. This was only exploitable in the template YAML definition itself and not by user input data.
Patches
This is vulnerability is fixed in version 1.15.0 of @backstage/plugin-scaffolder-backend.
Workarounds
Note that the Backstage Threat Model states that scaffolder templates are considered to be a sensitive area that with the recommendation that you control access and perform manual reviews of changes to the scaffolder templates. The exploit is of a nature where it is easily discoverable in manual review.
- Record
GHSA-wg6p-jmpc-xjmr- CVSS 3.1
- 8.0 High
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
NVD
8.0
Backstage is an open platform for building developer portals. The Backstage scaffolder-backend plugin uses a templating library that requires sandbox, as it by design allows for code injection. The library used for this sandbox so far has been vm2, but in light of several past vulnerabilities and existing vulnerabilities that may not have a fix, the plugin has switched to using a different sandbox library. A malicious actor with write access to a registered scaffolder template could manipulate the template in a way that allows for remote code execution on the scaffolder-backend instance. This was only exploitable in the template YAML definition itself and not by user input data. This is vulnerability is fixed in version 1.15.0 of @backstage/plugin-scaffolder-backend.
- Record
CVE-2023-35926- CVSS 3.1
- 8.0 High
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H - CVSS 3.1
- 9.9 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
OSV
8.0
Insecure sandbox in Backstage Scaffolder plugin
Backstage is an open platform for building developer portals. The Backstage scaffolder-backend plugin uses a templating library that requires sandbox, as it by design allows for code injection. The library used for this sandbox so far has been vm2, but in light of several past vulnerabilities and existing vulnerabilities that may not have a fix, the plugin has switched to using a different sandbox library. A malicious actor with write access to a registered scaffolder template could manipulate the template in a way that allows for remote code execution on the scaffolder-backend instance. This was only exploitable in the template YAML definition itself and not by user input data. This is vulnerability is fixed in version 1.15.0 of @backstage/plugin-scaffolder-backend.
- Record
CVE-2023-35926- CVSS 3.1
- 8.0 High
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
OSVGHSA-wg6p-jmpc-xjmr
8.0
Backstage Scaffolder plugin has insecure sandbox
The Backstage scaffolder-backend plugin uses a templating library that requires a sandbox, as it by design allows for code injection. The library used for this sandbox so far has been vm2, but in light of several past vulnerabilities and existing vulnerabilities that may not have a fix, the plugin has switched to using a different sandbox library.
Impact
A malicious actor with write access to a registered scaffolder template could manipulate the template in a way that allows for remote code execution on the scaffolder-backend instance. This was only exploitable in the template YAML definition itself and not by user input data.
Patches
This is vulnerability is fixed in version 1.15.0 of @backstage/plugin-scaffolder-backend.
Workarounds
Note that the Backstage Threat Model states that scaffolder templates are considered to be a sensitive area that with the recommendation that you control access and perform manual reviews of changes to the scaffolder templates. The exploit is of a nature where it is easily discoverable in manual review.
- Record
GHSA-wg6p-jmpc-xjmr- CVSS 3.1
- 8.0 High
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
@backstage/plugin-scaffolder-backendnpm |
before 1.15.0 | 1.15.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-35926 is a high vulnerability (CVSS 8.1) in Backstage, published June 21, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.89%, the 79th percentile. Fixed in @backstage/plugin-scaffolder-backend 1.15.0.
References
github.com/backstage/backstage/security/advisories/GHSA-wg6p-jmpc-xjmr
github.com/backstage/backstage/commit/fb7375507d56faedcb7bb3665480070593c8949a
github.com/backstage/backstage/releases/tag/v1.15.0
nvd.nist.gov/vuln/detail/CVE-2023-35926
github.com/advisories/GHSA-wg6p-jmpc-xjmr
github.com/CVEProject/cvelistV5/tree/main/cves/2023/35xxx/CVE-2023-35926.json
github.com/backstage/backstage