CVE-2021-41190 is a medium-severity (CVSS 5) CWE-843 vulnerability in github.com/opencontainers/distribution-spec. O3 Security confirms whether CVE-2021-41190 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Clarify Content-Type handling
Real-World Exposure
github.com/opencontainers/distribution-specReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
The OCI Distribution Spec project defines an API protocol to facilitate and standardize the distribution of content. In the OCI Distribution Specification version 1.0.0 and prior, the Content-Type header alone was used to determine the type of document during push and pull operations. Documents that contain both “manifests” and “layers” fields could be interpreted as either a manifest or an index in the absence of an accompanying Content-Type header. If a Content-Type header changed between two pulls of the same digest, a client may interpret the resulting content differently. The OCI Distribution Specification has been updated to require that a mediaType value present in a manifest or index match the Content-Type header used during the push and pull operations. Clients pulling from a registry may distrust the Content-Type header and reject an ambiguous document that contains both “manifests” and “layers” fields or “manifests” and “config” fields if they are unable to update to version 1.0.1 of the spec.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/opencontainers/distribution-spec | all versions | 1.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/opencontainers/distribution-spec. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/opencontainers/distribution-spec to 1.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41190 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2021-41190 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-41190. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
As a consequence of the OCI Image Specification (and OCI Distribution Specification [1]), container runtime engines (like containerd, moby - Docker Engine, cri-o) deliver updates to adopt new `mediaType` field used for identification of the document type. Even though some Red Hat products rely on container engine, the…
Frequently Asked Questions
Is CVE-2021-41190 in your dependencies?
O3 detects CVE-2021-41190 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.