CVE-2026-59950

HIGHNVD 8.18.1
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.1 under NVD CVSS v3. EPSS exploit probability: 0.2% (12th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
8.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 8.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.28.1, the deprecated mcp.server.websocket.websocket_server transport accepted WebSocket handshakes without applying Host or Origin header validation, leaving no SDK-level way to restrict which origins could connect to applications that exposed that transport. This issue is fixed in version 1.28.1.

CVSS v3
8.1
EG Score
8.1HIGHmedium confidence
EG Risk
37
EG Risk 37/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity81% × 45%
The EG Score, 8.1 of 10.
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 low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

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

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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)14 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 total (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

July 15, 2026

Last Modified

July 17, 2026

Advisory Details (4)

Auto-updated Jul 15, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
GitHub release Patch Available

v1.28.1

Patch available: modelcontextprotocol/python-sdk v1.28.1

https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1
GitHub commit

commit 777b8d06710c (modelcontextprotocol/python-sdk)

Fix landed in modelcontextprotocol/python-sdk commit 777b8d06710c — awaiting tagged release

https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266
GitHub pull request

[v1.x] Support TransportSecuritySettings in the WebSocket server transport

Fix merged in modelcontextprotocol/python-sdk PR #2992 on 2026-06-26 — awaiting tagged release

https://github.com/modelcontextprotocol/python-sdk/pull/2992
GitHub advisoryMentions a patch (unverified)

WebSocket server transport does not support Host/Origin validation · Advisory · modelcontextprotocol/python-sdk · GitHub

https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w

Vendor Advisories for CVE-2026-59950(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
mcp0.9.1 ... 1.9.4 (57 versions)
  • every version up to 1.28.1: fixed in 1.28.1
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 36× 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 135 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 35 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  2. 2026-10-13 15:42 UTCEG score recompute
  3. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  4. 2026-10-12 15:52 UTCEG score recompute
  5. 2026-10-11 19:36 UTCEG score recompute
  6. 2026-10-11 16:51 UTCEG score recompute
  7. 2026-10-11 14:13 UTCEG score recompute
  8. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  9. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  10. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  11. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  12. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  13. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  14. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  15. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  16. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  17. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  18. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  19. 2026-10-01 12:36 UTCEG score recompute
  20. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  21. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  22. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  23. 2026-09-28 08:41 UTCEG score recompute
  24. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  25. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 12th percentile
Show 75 more
  1. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  2. 2026-09-24 08:47 UTCEG score recompute
  3. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  4. 2026-09-23 03:14 UTCEG score recompute
  5. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  6. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  7. 2026-09-18 04:43 UTCEG score recompute
  8. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  9. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  10. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  11. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  12. 2026-09-13 23:11 UTCEG score recompute
  13. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-09-13 07:12 UTCEG score recompute
  15. 2026-09-11 21:44 UTCEG score recompute
  16. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  17. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  18. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  19. 2026-09-08 00:42 UTCEG score recompute
  20. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  21. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  22. 2026-09-05 20:47 UTCEG score recompute
  23. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  24. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  25. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  26. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  27. 2026-08-31 05:55 UTCEG score recompute
  28. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  29. 2026-08-30 03:45 UTCEG score recompute
  30. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  31. 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  32. 2026-08-27 21:27 UTCEG score recompute
  33. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  34. 2026-08-26 14:58 UTCEG score recompute
  35. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  36. 2026-08-26 01:37 UTCEG score recompute
  37. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  38. 2026-08-24 23:25 UTCEG score recompute
  39. 2026-08-24 10:21 UTCEG score recompute
  40. 2026-08-23 08:12 UTCEG score recompute
  41. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  42. 2026-08-22 06:00 UTCEG score recompute
  43. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  44. 2026-08-21 03:42 UTCEG score recompute
  45. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  46. 2026-08-20 00:13 UTCEG score recompute
  47. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  48. 2026-08-18 19:59 UTCEG score recompute
  49. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  50. 2026-08-17 23:11 UTCEG score recompute
  51. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  52. 2026-08-16 21:02 UTCEG score recompute
  53. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  54. 2026-08-16 07:57 UTCEG score recompute
  55. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  56. 2026-08-15 05:48 UTCEG score recompute
  57. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  58. 2026-08-14 03:38 UTCEG score recompute
  59. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  60. 2026-08-13 01:29 UTCEG score recompute
  61. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  62. 2026-08-11 23:20 UTCEG score recompute
  63. 2026-08-11 10:16 UTCEG score recompute
  64. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  65. 2026-08-09 19:03 UTCEG score recompute
  66. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  67. 2026-08-07 01:42 UTCEG score recompute
  68. 2026-08-06 13:47 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  69. 2026-08-05 23:34 UTCEG score recompute
  70. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  71. 2026-08-04 21:14 UTCEG score recompute
  72. 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  73. 2026-08-04 10:39 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  74. 2026-08-03 18:59 UTCEG score recompute
  75. 2026-08-03 10:36 UTCEPSS rescoreEPSS 0.1% · 4th percentile

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-59950?
CVE-2026-59950 is a high-severity vulnerability; its CVE record was published on July 15, 2026. The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.28.1, the deprecated mcp.server.websocket.websocket_server transport accepted WebSocket handshakes without applying Host or Origin header validation, leaving no SDK-level way to…
When was the CVE record for CVE-2026-59950 published?
The CVE record for CVE-2026-59950 was published on July 15, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of July 17, 2026; the record at its source may have been updated since.
Is CVE-2026-59950 actively exploited?
CVE-2026-59950 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-2026-59950?
CVE-2026-59950 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-59950?
A fix for CVE-2026-59950 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-59950 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-59950

Explore →

Is Your Infrastructure Affected by CVE-2026-59950?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs