Summary
Arcane’s updater service supported lifecycle labels com.getarcaneapp.arcane.lifecycle.pre-update and com.getarcaneapp.arcane.lifecycle.post-update that allowed defining a command to run before or after a container update. The label value is passed directly to /bin/sh -c without sanitization or validation.
Because any authenticated user (not limited to administrators) can create projects through the API, an attacker can create a project that specifies one of these lifecycle labels with a malicious command. When an administrator later triggers a container update (either manually or via scheduled update checks), Arcane reads the lifecycle label and executes its value as a shell command inside the container.
If the container is configured with host volume mounts in its Compose definition, the executed command may be able to read from or write to the host filesystem through the mounted paths. This can enable data theft and, in some configurations, escalation to full host compromise (for example, if /var/run/docker.sock is mounted).
Impact
- Remote code execution (RCE) within the updated container context.
- Host filesystem access when host volumes are mounted into the container.
- Potential data exfiltration via outbound network requests or by exposing readable files.
- Potential full host compromise if sensitive mounts are present (e.g., /var/run/docker.sock).
Untrusted input reaches a shell command, allowing arbitrary commands to run on the host. Typical impact: code execution in the application's environment.
CVE-2026-23520 has a CVSS score of 9.0 (Critical). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.0.0-20260114065515-5a9c2f92e11f); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
The lifecycle labels com.getarcaneapp.arcane.lifecycle.pre-update and com.getarcaneapp.arcane.lifecycle.post-update have been removed to eliminate this attack surface.
Frequently Asked Questions
- What is CVE-2026-23520? CVE-2026-23520 is a critical-severity OS command injection vulnerability in github.com/getarcaneapp/arcane/backend (go), affecting versions < 0.0.0-20260114065515-5a9c2f92e11f. It is fixed in 0.0.0-20260114065515-5a9c2f92e11f. Untrusted input reaches a shell command, allowing arbitrary commands to run on the host.
- How severe is CVE-2026-23520? CVE-2026-23520 has a CVSS score of 9.0 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/getarcaneapp/arcane/backend are affected by CVE-2026-23520? github.com/getarcaneapp/arcane/backend (go) versions < 0.0.0-20260114065515-5a9c2f92e11f is affected.
- Is there a fix for CVE-2026-23520? Yes. CVE-2026-23520 is fixed in 0.0.0-20260114065515-5a9c2f92e11f. Upgrade to this version or later.
- Is CVE-2026-23520 exploitable, and should I be worried? Whether CVE-2026-23520 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-23520 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-23520? Upgrade
github.com/getarcaneapp/arcane/backendto 0.0.0-20260114065515-5a9c2f92e11f or later.