EUVD-2026-30491Published

MCP Registry: Open Redirect

Collected exploitation and prediction evidence

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

cve-program · CVE-2026-44427

Published

The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. From 1.1.0 to 1.7.4, the TrailingSlashMiddleware in internal/api/server.go is vulnerable to an open redirect attack. An attacker can craft a URL with a protocol-relative path (e.g., //evil.com/) that, after trailing slash removal, results in a Location header of //evil.com — which browsers interpret as an absolute URL to an external domain. This vulnerability is fixed in 1.7.5.

Source published: 14 May 2026 21:07:34 UTC
Source modified: 15 May 2026 13:33:16 UTC
Observed here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

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CVSS 4.0 · 0.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N

euvd · EUVD-2026-30491

Published

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: May 14, 2026, 9:07:34 PM

dateUpdated: May 15, 2026, 1:33:16 PM

Source published: May 14, 2026, 9:07:34 PM (timezone not stated)
Source modified: May 15, 2026, 1:33:16 PM (timezone not stated)
Observed here: 28 Oct 2026 06:07:32 UTC
Source terms: ENISA EUVD · source terms and attribution apply

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nvd · CVE-2026-44427

Published

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Deferred

Weakness classifications: CWE-601

Original publisher date fields

published: 2026-05-14T22:16:44.450

lastModified: 2026-10-26T14:10:00.130

Source published: 14 May 2026 22:16:44 UTC
Source modified: 26 Oct 2026 14:10:00 UTC
Observed here: 27 Oct 2026 11:12:09 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

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CVSS 4.0 · [email protected] · Secondary · 0.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

osv · GHSA-v8vw-gw5j-w7m6

Published

### Summary The TrailingSlashMiddleware in internal/api/server.go is vulnerable to an open redirect attack. An attacker can craft a URL with a protocol-relative path (e.g., //evil.com/) that, after trailing slash removal, results in a Location header of //evil.com — which browsers interpret as an absolute URL to an external domain. ### Details The TrailingSlashMiddleware strips trailing slashes from request paths and issues a 308 Permanent Redirect to the cleaned path. However, it does not validate or sanitize the resulting path before using it as the redirect target. When a request is made with a path like //evil.com/, the middleware processes it as follows: ### PoC 1. Start the registry server locally or identify a deployed instance 2. Send a request with a double-slash path followed by an external domain: `curl -v https://<registry-host>//evil.com/` <img width="3066" height="969" alt="image" src="https://github.com/user-attachments/assets/a5305f00-29bf-4708-952a-478d608f2074" /> 3. Observe the 308 Permanent Redirect response with Location: //evil.com: 4. When accessed in a browser, the user is redirected to https://evil.com ### Impact **Phishing**: Attackers can abuse the trusted registry domain to redirect users to credential-harvesting pages **Malware distribution**: Redirect users to sites serving malicious downloads **Trust abuse:** Links originating from the official MCP Registry domain carry implicit trust

Source published: 8 May 2026 17:02:12 UTC
Source modified: 10 Sep 2026 03:50:47 UTC
Observed here: 24 Oct 2026 13:19:41 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

Publisher rating · MODERATE

osv · GO-2026-5658

Published

MCP Registry has open redirect via protocol-relative path in trailing-slash middleware in github.com/modelcontextprotocol/registry

Source published: 25 Jun 2026 22:34:38 UTC
Source modified: 25 Jun 2026 23:01:38 UTC
Observed here: 24 Oct 2026 13:19:41 UTC
Source terms: OSV · upstream source license applies

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