Is CVE-2025-62800 in the CISA KEV catalog?

No. CVE-2025-62800 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-62800?

CVE-2025-62800 has a CVSS v3 base score of 6.1 (MEDIUM).

What is the EPSS score for CVE-2025-62800?

CVE-2025-62800 has an EPSS score of 0.25% (16th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-62800?

Upgrade fastmcp to 2.13.0 or later.

CVE & CISA-KEV Catalog

CVE-2025-62800

MEDIUM

6.1

CVSS v3

NVD

Description

FastMCP is the standard framework for building MCP applications. Versions prior to 2.13.0 have a reflected cross-site scripting vulnerability in the OAuth client callback page (oauth_callback.py) where unescaped user-controlled values are inserted into the generated HTML, allowing arbitrary JavaScript execution in the callback server origin. The issue is fixed in version 2.13.0.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

fastmcpNVD

Affected:< 2.13.0Fixed in:2.13.0CVE-2025-62800derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploit Intelligence

0.25%probability of exploitation in 30 days

16thpercentile

Low risk: more likely to be exploited than 16% of all known CVEs.

References

Exploit1

github.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-07.