CVE-2026-12039: Docker Sandboxes · Improper Restriction of Communication Channel to Intended Endpoints
Affects Docker SandboxesSource CVE Database V5
Not known to be exploited · CVSS 5.7 Medium : upgrade to 0.33.0 when convenient.
Data as of 1 Nov 2026, 08:20 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 0% 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.
Description
Docker Sandboxes (sbx) enforces an HTTP/S-only egress allowlist but does not apply it to DNS resolution: the per-network embedded DNS server forwards any queried name to the host resolver whenever the network is internet-connected, without consulting the policy. A workload inside a sandbox, which the threat model treats as untrusted, can therefore encode data into DNS labels for an attacker-controlled domain and exfiltrate it through a DNS covert channel, bypassing the configured allowlist.