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TI-2026-70749 Aliases CVE-2026-108859GHSA-c673-ppxx-9wvj

mcp-go Denial of Service via Unbounded POST Body Buffering

Priority MEDIUM 44CWE-770Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 1 fixed, 1 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-770.

Summary

mcp-go through 1.2.1 has a denial of service flaw in StreamableHTTPServer.ServeHTTP that reads entire POST bodies into memory before validating them (CWE-770). A remote unauthenticated attacker can send oversized or many concurrent POST requests to exhaust server memory and crash the server process.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

mcp-go through 1.2.1 contains a denial of service vulnerability in StreamableHTTPServer.ServeHTTP that allows remote unauthenticated attackers to exhaust memory by sending oversized POST bodies. Attackers can send arbitrarily large or many concurrent POST requests, read fully via io.ReadAll before validation, to degrade or OOM-kill the server process.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00545 45th percentileScored 2026-11-07
Fix Partial Red Hat: 1 advisoryRed Hat: 1 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
mark3labsmcp-goup to 1.2.1—No fix listedCNA
  • mcp-go Vendormark3labs Affected up to 1.2.1 Fixed in — No fix listed CNA

Remediation

The sources list no fixed version for mcp-go. Red Hat OpenShift distributed tracing 3.11 is fixed by RHSA-2026:88187. Red Hat has no available plan for Red Hat Hardened Images, which is affected.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Red Hat 1 advisory

  • RHSA-2026:88187 Released 2026-10-22 · Red Hat rating Important
    Red Hat OpenShift distributed tracing platform (Tempo) 3.11.3 release
    • Red Hat OpenShift distributed tracing 3.11 registry.redhat.io/rhosdt/tempo-gateway-opa-rhel9, registry.redhat.io/rhosdt/tempo-gateway-rhel9, registry.redhat.io/rhosdt/tempo-jaeger-query-rhel9 +3

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Hardened ImagesAffectedNo fix yet
Red Hat OpenShift distributed tracing 3.11Fixed RHSA-2026:88187
Not affected: 3 products
  • Red Hat Connectivity Link 1
  • Red Hat OpenShift AI (RHOAI)
  • Red Hat OpenShift distributed tracing 3.11

Timeline

  1. 2026-10-11 Threatist record created from CVE-2026-108859
  2. 2026-10-11 Alias added: GHSA-c673-ppxx-9wvj
  3. 2026-10-12 Affected versions changed · Red Hat
  4. 2026-10-12 CVSS score added · Red Hat
  5. 2026-10-12 Priority changed: MEDIUM → LOW
  6. 2026-10-18 CISA SSVC decision points changed
  7. 2026-10-18 Priority changed: LOW → MEDIUM
  8. 2026-10-23 Fix available: RHSA-2026:88187 · Red Hat
  9. 2026-10-23 Fix available: Red Hat OpenShift distributed tracing 3.11.3 · Red Hat
  10. 2026-10-26 Fix available: Red Hat OpenShift distributed tracing 3.11 · Red Hat

References

Advisory 1

Other 2

  • TI-2026-56054 mcp-go before 0.56.0 Missing Host Header Validation Enables DNS Rebinding CVSS 4.0HIGH 7.6
  • TI-2026-85606 Origin validation error in mcp-go lets malicious servers obtain tokens CVSS 4.0MEDIUM 5.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences