CVE-2026-81092

MEDIUMPre-NVD 6.86.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 6.8 from GitHub Security Advisory (severity: HIGH) published 2026-08-27. A secondary CVSS source baseline 6.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week

Also known asEUVD-2026-67147 (ENISA EUVD) · GHSA-8g5x-gj7x-mxgm (GitHub Security Advisories)Source: ENISA EUVD

6.8EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 6.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

mcp-go accepted requests on its HTTP transports without checking the Host header. StreamableHTTPServer.ServeHTTP in server/streamable_http.go and SSEServer.ServeHTTP in server/sse.go served any request arriving over a loopback connection regardless of the host it named, and the SSE transport's cross-origin default allowed any origin. A page in a browser could therefore point a name it controlled at the loopback address and reach a server listening there, invoking tools and reading resources that the server exposed on the assumption that only local software could connect. No release before 0.56.0 validated the header on either transport; 0.56.0 adds server/http_localhost.go, which rejects a loopback-bound request carrying a host that is not a loopback name, and wires it into both transports.

CVSS v3
6.8
EG Score
6.8MEDIUMmedium confidence
EG Risk
31
EG Risk 31/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity68% × 45%
Impact severity (EG Severity): CVSS 6.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
12th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.8): severity, escalated by confirmed exploitation. This CVE's 6.8 is its impact severity (EG Severity), not escalated.

EG Severity
6.8 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 27, 2026

Last Modified

September 23, 2026

Advisory Details (4)

Auto-updated Aug 27, 2026
Patch available. Sources: github_pr, github_release.
Web page

mcp-go before 0.56.0 Missing Host Header Validation Enables DNS Rebinding | Advisories | VulnCheck

https://www.vulncheck.com/advisories/mcp-go-before-0.56.0-missing-host-header-validation-enables-dns-rebinding
GitHub release Patch Available

Release v0.56.0

Patch available: mark3labs/mcp-go v0.56.0

https://github.com/mark3labs/mcp-go/releases/tag/v0.56.0
GitHub pull request Patch Available

feat(server): add automatic DNS rebinding protection for localhost

Patch available: mark3labs/mcp-go v0.56.0 (PR #921 merged 2026-07-08)

https://github.com/mark3labs/mcp-go/pull/921
Web page

GitHub - mark3labs/mcp-go: A Go implementation of the Model Context Protocol (MCP), enabling seamless integration between LLM applications and external data sources and tools. · GitHub

https://github.com/mark3labs/mcp-go

Patch Availability(3)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhattempo3-0-main-3.0.3-0.2.hum12026-09-02redhat
redhattempo2-10-main-2.10.8-0.2.hum12026-09-02redhat
redhattempo3-0-main-3.0.3-0.1.hum12026-08-14redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 77× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 188 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 88 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  2. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  3. 2026-10-25 13:58 UTCEG score recompute
  4. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  5. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  6. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  7. 2026-10-22 13:53 UTCEG score recompute
  8. 2026-10-22 13:53 UTCVendor advisory
  9. 2026-10-22 13:53 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  10. 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  11. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  12. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  13. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  14. 2026-10-18 03:09 UTCEG score recompute
  15. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  16. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  17. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  18. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  19. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  20. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  21. 2026-10-12 14:57 UTCEG score recompute
  22. 2026-10-11 19:20 UTCEG score recompute
  23. 2026-10-11 16:37 UTCEG score recompute
  24. 2026-10-11 13:55 UTCEG score recompute
  25. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 11th percentile
Show 75 more
  1. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  2. 2026-10-10 02:09 UTCEG score recompute
  3. 2026-10-10 02:09 UTCVendor advisory
  4. 2026-10-10 02:09 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  5. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  6. 2026-10-09 03:08 UTCEG score recompute
  7. 2026-10-09 03:08 UTCVendor advisory
  8. 2026-10-09 03:07 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  9. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  10. 2026-10-08 01:21 UTCEG score recompute
  11. 2026-10-08 01:21 UTCVendor advisory
  12. 2026-10-08 01:20 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  14. 2026-10-06 23:55 UTCEG score recompute
  15. 2026-10-06 23:55 UTCVendor advisory
  16. 2026-10-06 23:55 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  17. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  18. 2026-10-06 00:54 UTCEG score recompute
  19. 2026-10-06 00:54 UTCVendor advisory
  20. 2026-10-06 00:54 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  21. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  22. 2026-10-05 01:23 UTCEG score recompute
  23. 2026-10-05 01:23 UTCVendor advisory
  24. 2026-10-05 01:23 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  25. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  26. 2026-10-04 01:54 UTCEG score recompute
  27. 2026-10-04 01:54 UTCVendor advisory
  28. 2026-10-04 01:54 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  29. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  30. 2026-10-03 02:41 UTCEG score recompute
  31. 2026-10-03 02:41 UTCVendor advisory
  32. 2026-10-03 02:41 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  33. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  34. 2026-10-02 03:39 UTCEG score recompute
  35. 2026-10-02 03:39 UTCVendor advisory
  36. 2026-10-02 03:39 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  37. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  38. 2026-10-01 04:06 UTCEG score recompute
  39. 2026-10-01 04:06 UTCVendor advisory
  40. 2026-10-01 04:05 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  41. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  42. 2026-09-30 05:03 UTCEG score recompute
  43. 2026-09-30 05:03 UTCVendor advisory
  44. 2026-09-30 05:03 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  45. 2026-09-28 21:17 UTCEG score recompute
  46. 2026-09-28 21:17 UTCVendor advisory
  47. 2026-09-28 21:17 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  48. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  49. 2026-09-27 17:47 UTCEG score recompute
  50. 2026-09-27 17:47 UTCVendor advisory
  51. 2026-09-27 17:47 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  52. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  53. 2026-09-26 18:45 UTCEG score recompute
  54. 2026-09-26 18:45 UTCVendor advisory
  55. 2026-09-26 18:45 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  56. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  57. 2026-09-25 15:49 UTCVendor advisory
  58. 2026-09-25 15:49 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  59. 2026-09-24 16:48 UTCEG score recompute
  60. 2026-09-24 16:48 UTCVendor advisory
  61. 2026-09-24 16:48 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  62. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.2% · 11th percentile
  63. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  64. 2026-09-23 17:25 UTCEG score recompute
  65. 2026-09-23 17:25 UTCVendor advisory
  66. 2026-09-23 17:25 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  67. 2026-09-23 15:39 UTCVendor advisory
  68. 2026-09-23 15:39 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  69. 2026-09-22 16:37 UTCEG score recompute
  70. 2026-09-22 16:37 UTCVendor advisory
  71. 2026-09-22 16:37 UTCGHSA enrichmentGHSA-8g5x-gj7x-mxgm · GitHub severity HIGH · GitHub CVSS 6.8
  72. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  73. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  74. 2026-09-21 17:20 UTCEG score recompute
  75. 2026-09-21 17:20 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-81092?
CVE-2026-81092 is a medium-severity vulnerability; its CVE record was published on August 27, 2026. mcp-go accepted requests on its HTTP transports without checking the Host header. StreamableHTTPServer.ServeHTTP in server/streamablehttp.go and SSEServer.ServeHTTP in server/sse.go served any request arriving over a loopback connection regardless of the host it named, and the SSE transport's…
When was CVE-2026-81092 made public?
CVE-2026-81092 was made public on August 26, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on August 27, 2026. EchelonGraph's copy of the record carries a last-modified date of September 23, 2026; the record at its source may have been updated since.
Is CVE-2026-81092 actively exploited?
CVE-2026-81092 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (12th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-81092?
CVE-2026-81092 has a CVSS base score of 6.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-81092?
A fix for CVE-2026-81092 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-81092 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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