CVE-2026-44428 MCP Registry: GitHub OIDC tokens replayable across registry deployments due to shared audience
Attackers can replay GitHub OIDC tokens across different MCP Registry deployments to gain unauthorized publish permissions due to shared audience validation.
- 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
What is CVE-2026-44428?
CVE-2026-44428 is a low-severity authentication bypass vulnerability in modelcontextprotocol registry, published on 14 May 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
The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.6, the client-side and server-side GitHub OIDC flow is bound only to a global audience string, not to the specific registry instance being targeted. On the client side, the publisher always appends audience=mcp-registry when requesting the GitHub Actions ID token, regardless of the selected --registry URL. On the server side, the exchange endpoint validates only that same fixed audience and then derives publish permissions directly from repository_owner. As a result, a token legitimately obtained while interacting with one registry deployment remains acceptable to any other deployment that shares the same code and audience string. This vulnerability is fixed in 1.7.6.
Weakness: CWE-918
Which versions are affected by CVE-2026-44428?
3 open source packages ship an affected version, including github.com/modelcontextprotocol/registry. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/modelcontextprotocol/registry Go | All versions | 1.7.6 |
github.com/modelcontextprotocol/registry Go | All versions | 1.7.6 |
github.com/modelcontextprotocol/registry Go | All versions | 1.7.6 |
Products include Lfprojects Mcp Registry.
How do I fix CVE-2026-44428?
Upgrade github.com/modelcontextprotocol/registry to 1.7.6 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-44428 being exploited?
There is no known exploitation of CVE-2026-44428 in the wild and no public exploit code.
Other vulnerabilities in modelcontextprotocol registry
Sources
Also known as GHSA-95c3-6vvw-4mrq, GO-2026-5273.