- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 15/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The Go library mark3labs/mcp-go, used for its client transport, is affected. A remote MCP server that sends a redirect can cause the client to send requests to arbitrary hosts and schemes, which allows server-side request forgery, and it also forwards configured custom headers and OAuth bearer tokens to those redirected destinations, exposing credentials.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
In github.com/mark3labs/mcp-go/client/transport, NewStreamableHTTP constructs an http.Client with a nil CheckRedirect policy when no custom WithHTTPBasicClient is supplied, and attaches static custom headers and OAuth bearer tokens inside a RoundTripper layer. If an MCP server responds with a 3xx redirect, the client follows the Location header to arbitrary hosts and schemes and attaches configured WithHeaders and OAuth Authorization headers to the redirected request, enabling server-side request forgery (SSRF) and credential disclosure.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure?/25Unknown. No advisory context yet
- Reach10/20Affects Go packages
- Severity?/10Unknown. No CVSS score or vendor rating
- No patch5/5No patch listed yet
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
- Would score about 37 if advisories confirm default setups are exposed
Timeline
- Advisory published
- Record last updated
- First seen by cve.now
Affected versions
- github.com/mark3labs/mcp-goGo
All versions
Evidence 2
- Report
- Report
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about GO-2026-6911
Is GO-2026-6911 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by GO-2026-6911?
github.com/mark3labs/mcp-go (Go): all versions.Source: cve.now feed data