# CVE-2026-92543: Docker Engine insecure-registry fallback via malicious DNS responses

> Attackers can bypass TLS certificate verification for Docker registries by manipulating DNS responses to include a loopback address, enabling man-in-the-middle attacks.

- **Severity:** High 7.6 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 7 Oct 2026
- **Updated:** 7 Oct 2026
- **Also known as:** AZL-107195, AZL-107315, AZL-107333, AZL-107351, AZL-107748, BELL-CVE-2026-92543, DEBIAN-CVE-2026-92543, ECHO-d9ac-ee9e-fee7, GHSA-7cfq-22r6-qp73, MINI-4hgx-rm7p-9vx8, MINI-4pq5-2vgq-q5f7, MINI-6236-wxjh-fxj7, MINI-jj7j-cfrc-pwvh, OESA-2026-4657, UBUNTU-CVE-2026-92543

## What is CVE-2026-92543?

CVE-2026-92543 is a high-severity vulnerability in Docker Engine, published on 7 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-319 (Cleartext Transmission of Sensitive Information), CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-92543?


## How do I fix CVE-2026-92543?

Apply the vendor's patch.

## Is CVE-2026-92543 being exploited?

There is no known exploitation of CVE-2026-92543 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-92543 and fix it if it is affected.

What it is: CVE-2026-92543 is a high-severity vulnerability in Docker Engine, published on 7 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-92543 in the wild and no public exploit code.

Affected product: Docker Engine. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-92543/ (Markdown: https://insights.sbomify.com/CVE-2026-92543/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-92543
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-92543
- OSV: https://osv.dev/vulnerability/CVE-2026-92543

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-92543/
Summaries are generated and may contain mistakes; the official description above is the record.