Vulnerability · Published Oct 13, 2026 · Assigned by GitHub_M

CVE-2026-53711MCP ContextForge: Global Prompts stored cross-site scripting compromises the Admin UI

Medium 5.1

In plain English

A medium-severity cross-site scripting in mcp-context-forge from IBM. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).

Severity (CVSS 4.0)5.1Medium

Exploit odds (30 days)0.4%top 69.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

MCP Context Forge provides an MCP Admin UI for managing gateway resources. From 0.2.0 until 0.3.1, the Global Prompts feature stores a prompt template without sufficient output encoding before the MCP Admin UI renders it. An authenticated attacker can save markup containing script-capable event handlers, and the code executes when another user views the saved prompt. The stored cross-site scripting can alter the interface, present phishing content, observe keystrokes available to the page, and act with the viewer's browser session. This issue is fixed in version 0.3.1.

Affected products (as reported)

Vendor	Product	Versions
IBM	mcp-context-forge	>= 0.2.0, < 0.3.1

Weakness: CWE-79 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

References

https://github.com/IBM/mcp-context-forge/security/advisories/GHSA-x6gc-rm5j-55mw x_refsource_CONFIRM
https://github.com/IBM/mcp-context-forge/pull/337 x_refsource_MISC
https://github.com/IBM/mcp-context-forge/commit/acd16196158f9a393187551b21a2fc61650f2e3d x_refsource_MISC
https://github.com/IBM/mcp-context-forge/releases/tag/v0.3.1 x_refsource_MISC