The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). From 1.23.0 until 1.27.2, default handlers installed by server.experimental.enable_tasks() for tasks/list, tasks/get, tasks/result, and tasks/cancel operate only on task identifiers without recording the session that created each task, allowing any connected client to enumerate, read results from, consume messages for, or cancel other clients' tasks. This issue is fixed in version 1.27.2.
CVE-2026-52870
HIGHPre-NVD 7.67.6—
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 87% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
7.6
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.6Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.6
- EG Score
- 7.6(medium)
- EG Risk
- —
- EPSS
- 13.0%
- KEV
- Not listed
Published
July 15, 2026
Last Modified
July 17, 2026
Advisory Details (4)
Auto-updated Jul 15, 2026Patch available. Sources: github, github_commit, github_pr, github_release.
github Patch Available
Experimental task handlers allow any client to access and cancel other clients' tasks · Advisory · modelcontextprotocol/python-sdk · GitHub
https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775github_release Patch Available
v1.27.2
Patch available: modelcontextprotocol/python-sdk v1.27.2
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2github_pr Patch Available
[v1.x] Scope experimental tasks to the session that created them
Patch available: modelcontextprotocol/python-sdk v1.27.2 (PR #2720 merged 2026-05-29)
https://github.com/modelcontextprotocol/python-sdk/pull/2720github_commit Patch Available
commit 62137874ff26 (modelcontextprotocol/python-sdk)
Patch available: modelcontextprotocol/python-sdk v1.27.2 (contains commit 62137874ff26)
https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7Vendor Advisories for CVE-2026-52870(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)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| mcp | 1.23.0 ... 1.27.1 (9 versions) | 1.27.2 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 11× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:25 UTCEPSS rescore
- 2026-07-20 17:08 UTCEPSS rescore
- 2026-07-19 14:31 UTCEPSS rescore
- 2026-07-19 14:31 UTCEPSS rescore
- 2026-07-19 02:37 UTCEG score recompute
- 2026-07-19 02:29 UTCEPSS rescore
- 2026-07-18 10:04 UTCEPSS rescore
- 2026-07-16 17:03 UTCEPSS rescore
- 2026-07-15 20:10 UTCEG score recompute
- 2026-07-15 20:09 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Same CWE
10 shownCWE-862
Frequently asked(5)
What is CVE-2026-52870?
CVE-2026-52870 is a high vulnerability published on July 15, 2026. The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). From 1.23.0 until 1.27.2, default handlers installed by server.experimental.enable_tasks() for tasks/list, tasks/get, tasks/result, and tasks/cancel operate only on task identifiers without…
When was CVE-2026-52870 disclosed?
CVE-2026-52870 was first published in the National Vulnerability Database on July 15, 2026, with the most recent update on July 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-52870 actively exploited?
CVE-2026-52870 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 13.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-52870?
CVE-2026-52870 has a CVSS v3 base score of 7.6 (NVD).
How do I remediate CVE-2026-52870?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-52870, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-52870
Is Your Infrastructure Affected by CVE-2026-52870?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.