CVE-2026-12539: Docker Sandboxes · Improper Restriction of Communication Channel to Intended Endpoints
Affects Docker SandboxesSource CVE Database V5
Not known to be exploited · CVSS 5.1 Medium : upgrade to 0.33.0 when convenient.
Data as of 31 Oct 2026, 20:20 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.33.0
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 18 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.
What to do
Upgrade Docker Sandboxes to 0.33.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| DockerDocker Sandboxes | Affected
| Fixed in
|
GitHubdocker/sbx-releasespkg:github/docker/sbx-releasesOther threats | Affected
| Fixed in– |
CPE configurations (1)
cpe:2.3:a:docker:docker_sandboxes:*:*:*:*:*:*:*:*
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, administrators should be aware that Docker daemon restarts may temporarily disable ICMP egress restrictions in Docker Sandboxes. Consider avoiding reliance solely on ICMP egress blocking for sensitive workloads or implement additional network monitoring and controls to detect anomalous ICMP traffic.
Description
Docker Sandboxes (sbx) blocks ICMP egress with an authorizer applied only at network-creation time, and does not re-apply it to networks rebuilt from disk when the Docker daemon restarts, so a restart-surviving sandbox forwards ICMP to arbitrary hosts. A workload inside a sandbox, which the threat model treats as untrusted, can therefore defeat the documented ICMP egress block to perform network reconnaissance and exfiltrate data over an ICMP covert channel, regardless of the configured allowlist.