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OpenCode flaw lets malicious MCP servers run code at sign-in

What to do

Update OpenCode to 1.18.33 if you use it on Windows or WSL with MCP servers.

Why

Versions 1.0.137 through 1.18.32 run code from a malicious MCP server via the OAuth endpoint, and the fix shipped September 28 without a CVE.

Read the source at thehackernews.com

What the research found

OpenCode versions 1.0.137 through 1.18.32 on Windows and WSL allow a malicious MCP server to run code via OAuth authorization endpoint during sign-in; fixed in 1.18.33 on September 28 with no CVE or advisory.

Claims and how well the evidence supports them

OpenCode fixed the flaw in version 1.18.33 on September 28 99%
Affected builds are 1.0.137 through 1.18.32 on Windows and WSL 98%
No CVE was requested and no security advisory was published 99%
Pillar Security rates the flaw critical with a proposed score of 9.8 99%

Evidence

thehackernews.com https://thehackernews.com/2026/10/opencode-flaw-lets-malicious-mcp.html

Actionability rated high.