CVE-2023-35926Network attack vector

Remote code execution via vm2 sandbox escape

Published Jun 22, 2023 · Updated Dec 5, 2024

Code injection in Backstage Scaffolder Backend before 1.15.0 allows remote authenticated users to execute code via a crafted template. SecureTemplater evaluates Nunjucks template expressions inside vm2, whose sandbox does not reliably isolate attacker-supplied JavaScript. Exploitation requires write access to a registered template's YAML definition, not control of ordinary template input, and yields code execution on the backend instance.

CVSS severity8.0
High
EPSS probability1.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in Backstage Scaffolder Backend before 1.15.0 allows remote authenticated users to execute code via a crafted template. SecureTemplater evaluates Nunjucks template expressions inside vm2, whose sandbox does not reliably isolate attacker-supplied JavaScript. Exploitation requires write access to a registered template's YAML definition, not control of ordinary template input, and yields code execution on the backend instance.

The record

CVE
CVE-2023-35926
Published
Jun 22, 2023
Updated
Dec 5, 2024
Vendor
Backstage
Product
Backstage
Classifications
CWE-94, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.15.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Backstage · Backstageversion=< 1.15.0

Published CVSS scores

9.9NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
8.0GitHubCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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