8.1

CVE-2026-34742: lfprojects mcp_go_sdk

CVSS: 8.1v3.1HighModified
AliasesCGA-9f7w-grrq-4qq2CGA-g77c-r65f-php7GHSA-xw59-hvm2-8pj6
Published 02-04-2026Last modified 15-07-2026
Open JSON

Vulnerability summary

CVE-2026-34742 is a high (CVSS 8.1) vulnerability in lfprojects mcp_go_sdk. EPSS estimates a 0.66% chance of exploitation in the next 30 days, higher than 50.8% of scored vulnerabilities.

Overall risk
33/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.1/10
010
High · v3.1 (NVD)
EPSS score
0.66%
0%100%
Low · +0.21 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:21483-1

Timeline

  1. 02-04-2026
    PublishedVulnerability first disclosed.
  2. 15-07-2026
    Last modifiedVulnerability information updated.

Description

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 metrics

8 scores · 5 sources · 2 versions

EPSS trend

Probability

0.66%

Chance of exploitation in the next 30 days

Percentile

51%

Versus all other CVEs

30-day change

+0.21 pp

From 0.46% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.66%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard6 products
  • datadog-cluster-agent-7.75All versions (No fix recorded)
  • datadog-cluster-agent-fips-7.75All versions (No fix recorded)
  • gitlab-workhorse-ce-18.6All versions (No fix recorded)
  • gitlab-workhorse-ce-18.7All versions (No fix recorded)
  • gitlab-workhorse-ce-fips-18.6All versions (No fix recorded)
Github.com/modelcontextprotocol1 product
  • go-sdk< 1.4.0
Lfprojects1 product
Modelcontextprotocol1 product
Wolfi1 product
  • datadog-cluster-agent-7.75All versions (No fix recorded)

5 vendors · 10 products

References

11 links
Show all 11 references