Unauthorized publishing via cross-registry OIDC token replay
Published May 14, 2026 · Updated May 14, 2026
Authentication bypass in Model Context Protocol MCP Registry before 1.7.6 allows remote attackers to publish under a victim GitHub namespace. The publisher requests a fixed mcp-registry audience, while /v0/auth/github-oidc accepts that audience and derives publish rights from repository_owner without binding the token to the target deployment. Exploitation requires a GitHub Actions workflow to send its token first to a compromised or attacker-controlled registry, which must replay it before expiration.
Summary
What happened
Authentication bypass in Model Context Protocol MCP Registry before 1.7.6 allows remote attackers to publish under a victim GitHub namespace. The publisher requests a fixed mcp-registry audience, while /v0/auth/github-oidc accepts that audience and derives publish rights from repository_owner without binding the token to the target deployment. Exploitation requires a GitHub Actions workflow to send its token first to a compromised or attacker-controlled registry, which must replay it before expiration.
The record
- CVE
- CVE-2026-44428
- Published
- May 14, 2026
- Updated
- May 14, 2026
- Vendor
- Model Context Protocol
- Product
- MCP Registry
- Classifications
- CWE-918, CAPEC-664, T1550.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 14, 2026CVE publishedPublication date reported by the CVE source.
- May 14, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.7.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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