critical CVSS 9.8 EPSS 0.45%

CVE-2026-23944·Docker vulnerability

Arcane is an interface for managing Docker containers, images, networks, and volumes. Prior to version 1.13.2, unauthenticated requests could be proxied to remote environment agents, allowing access to remote environment resources without authentication. The environment proxy middleware handled `/api/environments/{id}/...` requests for remote environments before authentication was enforced. When the environment ID was not local, the middleware proxied the request and attached the manager-held agent token, even if the caller was unauthenticated. This enabled unauthenticated access to remote environment operations (e.g., listing containers, streaming logs, or other agent endpoints). An unauthenticated attacker could access and manipulate remote environment resources via the proxy, potentially leading to data exposure, unauthorized changes, or service disruption. Version 1.13.2 patches the vulnerability.

Severity
critical
Software
Docker
Fixed in
1.13.2
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.45% — higher than 37% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2026-23944 scores 9.8 on CVSS, so a successful attack would be serious — but at 0.45%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

Until: 1.13.2

Fixed in: 1.13.2

How to fix this CVE

Upgrade Docker to version 1.13.2 or later to patch an authentication bypass in the environment proxy middleware. Prior versions allowed unauthenticated attackers to access remote environment resources by proxying requests without proper credential validation. Apply the update immediately to prevent unauthorized access to container operations and remote resources.

sudo dnf update docker-ce

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|GET /api/environments/[a-f0-9-]{36}/[^\s]+ HTTP/1\.[01] .{0,500}(401|403|Unauthorized) response absent; successful container list, image pull, or log stream operations without Bearer token in Authorization header

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement authentication enforcement before routing /api/environments/{id}/* requests to proxy handlers. Block requests to this endpoint path that lack valid Bearer token or session cookie credentials. Enforce origin validation to prevent cross-environment token reuse.

How to check if you are affected

  1. Check the installed Docker version: docker --version
  2. Verify if Arcane environment proxy is enabled: grep -r 'environment.*proxy' /etc/docker/ /var/lib/docker/config/ 2>/dev/null
  3. Search Docker daemon logs for unauthenticated proxy requests: journalctl -u docker -S '24 hours ago' | grep -E '(unauthenticated|proxy|/api/environments)' | head -20
  4. Confirm the patch is applied: docker --version | grep -E '(1\.13\.[2-9]|1\.(14|15|16))' && echo 'Patched' || echo 'Vulnerable'

FAQ

What is CVE-2026-23944?

CVE-2026-23944 is a critical authentication bypass vulnerability in Docker's Arcane environment proxy middleware that allows unauthenticated attackers to access and manipulate remote environment resources, including containers, logs, and volumes, by proxying API requests with elevated credentials.

Is CVE-2026-23944 being actively exploited?

No, there are no confirmed reports of active exploitation or publicly available exploits, but the critical CVSS score (9.8) and simplicity of the attack vector make immediate patching essential.

What versions of Docker are affected by CVE-2026-23944?

All versions prior to 1.13.2 are affected; Docker versions 1.13.2 and later contain the security patch.

How do I check if my server is vulnerable to CVE-2026-23944?

Run 'docker --version' and compare the version number. If it is below 1.13.2, your installation is vulnerable. Additionally, check if unauthenticated requests to /api/environments/{id}/... endpoints return 200 responses instead of 401 Unauthorized.

Does Defensia detect CVE-2026-23944?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Docker is installed on a monitored server, CVE-2026-23944 will appear in your dashboard with remediation steps.

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References

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