CVE-2026-23520: Arcane Has a Command Injection in Arcane Updater Lifecycle Labels That Enables RCE

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 1.8%, percentile 79: FIRST’s model estimates a 1.8% chance of exploitation activity in the next 30 days, higher than 79% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes github.com/getarcaneapp/arcane/backend (Go) < 0.0.0-20260114065515-5a9c2f92e11f, fixed in 0.0.0-20260114065515-5a9c2f92e11f. Check your lockfile, including transitive dependencies.

What it is

Arcane provides modern docker management. Prior to 1.13.0, Arcane has a command injection in the updater service. 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. This vulnerability is fixed in 1.13.0.

From the GitHub advisory

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

Weakness type: CWE-78.

Product: github.com/getarcaneapp/arcane/backend (Go) · Assigned by: GitHub_M · Published: 2026-01-15

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: required (a user must click/open something)
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.85% probability of exploitation activity in the next 30 days; percentile 79.

Timeline

• 2026-01-15 — CVE record last updated
• 2026-01-15 — CVE record published by GitHub_M
• 2026-01-15 — GitHub-reviewed advisory GHSA-gjqq-6r35-w3r8 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-gjqq-6r35-w3r8 github.com
2. CVE.org record CVE-2026-23520 cve.org
3. NVD entry CVE-2026-23520 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

Critical Go advisories · Today’s Security Digest