{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-123272 in the wild and no public exploit code.","exposure":"","fix":"No fix has been published for CVE-2026-123272 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-123272 is a medium-severity vulnerability in mark3labs mcp-go, published on 5 Nov 2026."},"fix_prompt":"Check this codebase for CVE-2026-123272 and fix it if it is affected.\n\nWhat it is: CVE-2026-123272 is a medium-severity vulnerability in mark3labs mcp-go, published on 5 Nov 2026. \nExploitation: There is no known exploitation of CVE-2026-123272 in the wild and no public exploit code.\n\nAffected product: mark3labs mcp-go. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-123272/ (Markdown: https://insights.sbomify.com/CVE-2026-123272/index.md)","id":"CVE-2026-123272","markdown":"https://insights.sbomify.com/CVE-2026-123272/index.md","name":"CVE-2026-123272","record":{"aliases":["GHSA-h3x9-8c36-m89w","GHSA-xf6j-693p-wqxx"],"analysis":null,"analysis_generated_by":null,"assigner":"VulnCheck","cpe":[],"cvss":{"score":5.1,"severity":"medium","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N","version":"4.0"},"cwes":[{"id":"CWE-346","name":"Origin Validation Error"}],"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.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":false,"headline":"mcp-go before v1.2.1 Origin Validation Error via Unvalidated Well-Known Protected Resource Metadata","id":"CVE-2026-123272","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":null,"year":"2026"},"n_packages":0,"n_references":6,"next":{"headline":"ImageMagick before 7.1.2-35 and 6.9.13-60 Infinite Loop via SVG Decoder","id":"CVE-2026-123273"},"nickname":null,"packages":[],"prev":{"headline":"ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator","id":"CVE-2026-123271"},"products":["mcp-go"],"published":"2026-11-05","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-11-08","vendors":["mark3labs"]},"summary":null,"url":"https://insights.sbomify.com/CVE-2026-123272/"}