Harsha Hegde@HarshaHegde0
Mcp-go https://nvd.nist.gov/vuln/detail/cve-2026-123272 ChatCli https://nvd.nist.gov/vuln/detail/cve-2026-123271
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CVE-2026-123272
LOWCVSS 5.1 · MEDIUMSignal is active with 1 mentions in latest observed window
Immediate actions
- Track advisory updates for patch or workaround availability
Recommended action window: Monitor and triage in normal cycle
NVD description
Mark3labs mcp-go before v1.2.1 contains an improper validation vulnerability in OAuthHandler.fetchServerMetadata that allows malicious MCP servers to obtain tokens for other resources by declaring arbitrary resources in well-known metadata. Attackers can declare a different MCP server as the RFC 8707 resource indicator, causing the authorization server to mint tokens the attacker replays against that resource.
0.0/ 10 priority
Sources & remediation
Other references
- https://github.com/mark3labs/mcp-go/blob/4cb0d2015f24b669726fd8e5e53fc8c6d3f57abf/client/transport/oauth.go#L799-L821
- https://github.com/mark3labs/mcp-go/commit/90d247ed8d45cbb7d71d9a95e112789b78760443
- https://github.com/mark3labs/mcp-go/pull/1053
- https://github.com/mark3labs/mcp-go/releases/tag/v1.2.1
- https://github.com/mark3labs/mcp-go/security/advisories/GHSA-xf6j-693p-wqxx
Weakness type (CWE)
CWE-346
Priority
LOW
Exploitation
NONE
PoC
NONE
Patch
NONE
Momentum
NONE
Threat summary
- 1 mentions across 1 observed day
What's happening
- 1 total mentions across 1 day