Is CVE-2026-12039 in the CISA KEV catalog?

No. CVE-2026-12039 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-12039?

CVE-2026-12039 has a CVSS v4 base score of 5.7 (MEDIUM).

What is the EPSS score for CVE-2026-12039?

CVE-2026-12039 has an EPSS score of 0.10% (1th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-12039?

No published fix for CVE-2026-12039 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-12039

MEDIUM

5.7

CVSS v4

NVD

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.

CWE-923

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v4 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

Impact

CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Exploit Intelligence

0.10%probability of exploitation in 30 days

1stpercentile

Low risk: more likely to be exploited than 1% of all known CVEs.

References

Other references2

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-30.