CVE-2026-34742The Go MCP SDK used Go's standard encoding/json.
Updated under an hour ago ()
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It affects lfprojects mcp_go_sdk. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with StreamableHTTPHandler or SSEHandler, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. This issue has been patched in version 1.4.0.
- CVSS
- 8.1 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
- Weakness (CWE)
- CWE-1188
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Jul 24, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
lfprojects mcp_go_sdk lfprojects:mcp_go_sdk | before 1.4.0 | NVD |
References
- https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6dpatch
- https://github.com/modelcontextprotocol/go-sdk/pull/760issue-tracking, patch
- https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0release-notes
- https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:21772
- https://access.redhat.com/security/cve/CVE-2026-34742
- https://bugzilla.redhat.com/show_bug.cgi?id=2454608
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34742.json
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.