Docker Engine insecure-registry fallback via malicious DNS responses
Summary
| CVE | CVE-2026-92543 |
|---|---|
| State | PUBLISHED |
| Assigner | Docker |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-07 17:17:02 UTC |
| Updated | 2026-10-08 20:46:35 UTC |
| Description | Docker Engine classifies a registry hostname as insecure using an any-match DNS check. loadInsecureRegistries() injects 127.0.0.0/8 and ::1/128 as insecure CIDRs by default. isCIDRMatch resolves all of the hostname's addresses and returns true if a single address is in the insecure CIDR list. Because the transport re-dials the hostname rather than the CIDR-matching address, a DNS answer set of one loopback IP plus a non-loopback attacker IP disables certificate verification and enables HTTP fallback for the registry connection. |
Risk And Classification
Primary CVSS: v4.0 7.6 HIGH from [email protected]
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/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
EPSS: 0.000870000 probability, percentile 0.003490000 (date 2026-10-10)
Problem Types: CWE-295 | CWE-319 | CWE-295 CWE-295: Improper Certificate Validation | CWE-319 CWE-319: Cleartext Transmission of Sensitive Information
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 7.6 | HIGH | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 7.6 | HIGH | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/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
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Docker | Docker Engine | affected 29.8.2 semver | Not specified |
| CNA | Moby | Moby | affected v2.0.0-beta.25 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/moby/moby/security/advisories/GHSA-7cfq-22r6-qp73 | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Adam Korczynski of ADA Logics (en)
Additional Advisory Data
Workarounds
CNA: If upgrading is not immediately possible, ensure that registry hostnames resolve only to trusted, non-loopback IP addresses. For example, administrators can use a trusted DNS configuration or a local hosts-file entry to pin the registry hostname to its expected address. Alternatively, restrict outbound network access from the Docker daemon so that registry connections can only reach trusted registry endpoints. Removing entries from the insecure-registries configuration is not sufficient, because Docker Engine automatically treats the 127.0.0.0/8 and ::1/128 ranges as insecure. Using a trusted CA certificate for the registry does not mitigate this issue if the registry hostname can also resolve to a loopback address, because the resulting registry configuration permits connections without certificate verification. As a defense in depth against image substitution, images can be referenced by digest rather than by a mutable tag. This does not prevent disclosure of registry credentials and should not be considered a complete workaround.