CVE-2026-52870: The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP)

Routine

HIGH 7.6UPGRADE

CVE-2026-52870 is a high-severity flaw (CVSS 7.6) affecting mcp python sdk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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'

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 68%)
CISA exploited list	No
Weakness	CWE-862
Published	2026-07-15
Last modified	2026-10-24

Publisher (CNA): GitHub, Inc. · Vendor: lfprojects

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-15 20:17 UTCPublished CVE record published
2026-10-24 21:10 UTCUpdated Record last modified

lfprojects mcp python sdk UPGRADE

Affected: >= 1.23.0 and < 1.27.2

Fixed in: 1.27.2

Safe to downgrade to: a release before 1.23.0

1. Check installed version

apt-cache policy mcp-python-sdk || rpm -q mcp-python-sdk || mcp-python-sdk --version

2. UPGRADE to 1.27.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mcp-python-sdk

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mcp-python-sdk

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.23.0 (Debian / Ubuntu)

apt-cache madison mcp-python-sdk sudo apt install mcp-python-sdk=<VERSION_BEFORE_1.23.0> sudo apt-mark hold mcp-python-sdk

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list mcp-python-sdk sudo dnf downgrade mcp-python-sdk-<VERSION_BEFORE_1.23.0> sudo dnf versionlock add mcp-python-sdk

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-52870?

mcp python sdk: upgrade to 1.27.2. Exact commands for each OS are on this page.

Is CVE-2026-52870 being exploited?

CVE-2026-52870 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-52870 affect?

CVE-2026-52870 affects mcp python sdk. Severity is high (CVSS 7.6). 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

How urgent is CVE-2026-52870?

Priority 35/100. High severity

Software pages

Python vulnerabilities · PyPI packages vulnerabilities

Related CVEs

CVE-2026-52869 HIGH 7.1 UPGRADE The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP)
CVE-2026-59950 HIGH 8.1 UPGRADE The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP)

References

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