# CVE-2026-44428: Model Context Protocol Registry OIDC token replay via shared audience

Source: https://junglewise.ai/threats/cve-2026-44428-model-context-protocol-registry-oidc-token-replay-via-shared  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-14. Updated: 2026-05-16  
License: CC BY 4.0 with a link back

CVE-2026-44428 · Severity: medium · CVSS 4.7 · Published 2026-05-14

The MCP Registry, a tool for managing and publishing software packages, contains a flaw in how it handles GitHub authentication. Because different installations of the registry share the same identification settings, a security token used for one registry can be reused on another. This could allow a malicious or compromised registry to impersonate a legitimate user and publish unauthorized software updates under that user's name on a different registry instance.

Technologies: [github.com/modelcontextprotocol/registry (Go)](https://junglewise.ai/threats/technologies/github-com-modelcontextprotocol-registry), [Model Context Protocol Registry](https://junglewise.ai/threats/technologies/registry). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Model Context Protocol](https://junglewise.ai/threats/vendors/model-context-protocol).

## Quick answers

**Is CVE-2026-44428 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44428 being exploited in the wild.

**How severe is CVE-2026-44428?** Medium severity, with a CVSS score of 4.7, published 14 May 2026.

**Which products and versions are affected?** github.com/modelcontextprotocol/registry (Go) < 1.7.6, SEMVER:introduced=0,fixed=1.7.6; Model Context Protocol Registry < 1.7.6; Model Context Protocol Registry < 1.7.6.

**Is there a fix for CVE-2026-44428?** Yes. github.com/modelcontextprotocol/registry (Go): upgrade to 1.7.6 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44428 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-44428?** Check whether you run github.com/modelcontextprotocol/registry (Go), Model Context Protocol Registry or Model Context Protocol Registry at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/modelcontextprotocol/registry (Go): upgrade to 1.7.6 or later

  ```sh
  go get github.com/modelcontextprotocol/registry@v1.7.6
  ```


## Technical details

The MCP Registry's GitHub OIDC implementation uses a hardcoded global audience string ('mcp-registry') for both client-side token requests and server-side validation. When a user authenticates to a registry (e.g., a staging or attacker-controlled instance), the publisher requests a GitHub ID token with this shared audience. Because the server-side validation logic in 'internal/api/handlers/v0/auth/github_oidc.go' only checks for this fixed string and does not verify the specific registry instance URL, the token can be replayed to any other MCP Registry deployment. An attacker who observes this token can exchange it for a registry JWT, gaining 'io.github.<owner>/*' publish permissions on the victim registry. This has been patched in version 1.7.6 by implementing instance-specific audience validation.

## Affected products

- modelcontextprotocol registry < 1.7.6

## Identifiers

- CVE-2026-44428
- GHSA-95c3-6vvw-4mrq
- GO-2026-5273

## Timeline

- 2026-05-04: disclosed
- 2026-05-08: advisory
- 2026-05-08: patched: Fixed in version 1.7.6

## References

- [https://api.github.com/users/FORIMOC](https://api.github.com/users/FORIMOC)
- [https://github.com/FORIMOC](https://github.com/FORIMOC)
- [https://api.github.com/users/FORIMOC/gists%7B/gist_id%7D](https://api.github.com/users/FORIMOC/gists%7B/gist_id%7D)
- [https://api.github.com/users/FORIMOC/repos](https://api.github.com/users/FORIMOC/repos)
- [https://avatars.githubusercontent.com/u/73113688?v=4](https://avatars.githubusercontent.com/u/73113688?v=4)
- [https://api.github.com/users/FORIMOC/events%7B/privacy%7D](https://api.github.com/users/FORIMOC/events%7B/privacy%7D)

## Related threats

- [Model Context Protocol Registry open redirect in TrailingSlashMiddleware](https://junglewise.ai/threats/cve-2026-44427-model-context-protocol-registry-open-redirect-in)
- [Model Context Protocol Registry ownership bypass in OCI validator](https://junglewise.ai/threats/cve-2026-45781-model-context-protocol-registry-ownership-bypass-in-oci-validator)
- [Model Context Protocol Registry SSRF via IPv6 Filter Bypass](https://junglewise.ai/threats/cve-2026-44430-model-context-protocol-registry-ssrf-via-ipv6-filter-bypass)
- [MCP Registry stored XSS in catalogue UI via websiteUrl](https://junglewise.ai/threats/cve-2026-44429-mcp-registry-stored-xss-in-catalogue-ui-via-websiteurl)