CVE-2026-107503: Eclipse Ditto Auth Bypass Vulnerability

CVE-2026-107503 Overview

CVE-2026-107503 is a high-severity vulnerability in Eclipse Ditto affecting the Explorer UI and Swagger UI OpenID Connect (OIDC) integrations. The Explorer UI loads its complete environment configuration, including the Ditto API URI and OIDC provider settings, from an arbitrary cross-origin URL supplied through the environmentsURL query parameter. The configuration is adopted without user confirmation and persisted in the browser's localStorage. A crafted link allows an attacker to redirect OIDC token exchange or API traffic to an attacker-controlled endpoint, enabling theft of access tokens, refresh tokens, or Basic credentials.

Critical Impact
A single crafted link can persistently hijack a victim's Ditto session, exfiltrating OIDC tokens or bearer credentials on every subsequent visit to the UI.

Affected Products

Eclipse Ditto Explorer UI versions 3.6.0 through 3.8.13
Eclipse Ditto Explorer UI versions 3.9.0 through 3.9.7
Eclipse Ditto Swagger UI OIDC integration (Helm chart and Docker Compose) versions 3.9.0 through 3.9.7

Discovery Timeline

2026-10-08 - CVE-2026-107503 published to NVD
2026-10-15 - Last updated in NVD database

Technical Details for CVE-2026-107503

Vulnerability Analysis

The flaw is an [CWE-15] External Control of System or Configuration Setting weakness in the Eclipse Ditto Explorer UI. The UI accepts an environmentsURL query parameter and fetches its runtime configuration from the specified URL without validating the origin. The returned configuration includes the Ditto API URI, OIDC authority, and autoSso flag. Because the configuration is persisted in localStorage, any later visit to the UI reuses the attacker-controlled values even when the crafted link is not reused.

Two exploitation paths are available. In the OIDC path, the attacker sets an authority they control with autoSso enabled; the UI starts a legitimate login at the real identity provider but exchanges the authorization code and PKCE code_verifier at the attacker's token endpoint, surrendering the victim's access and refresh tokens. In the API path, an attacker-controlled api_uri causes the UI to transmit the victim's bearer token or Basic credentials directly to the attacker.

Root Cause

The UI treats the environmentsURL parameter as trusted input. There is no origin allowlist, no user confirmation prompt before adopting the fetched configuration, and no scoping of persisted settings. The Swagger UI OIDC integration shipped with the Helm chart and Docker Compose deployment reuses the same loading logic and inherits the same defect.

Attack Vector

Exploitation requires a user to click a crafted link to a legitimate Ditto Explorer UI deployment. The link embeds an environmentsURL pointing to attacker-controlled JSON. User interaction is limited to visiting the link; for the Swagger UI variant the user must additionally initiate login.

javascript

// Patch excerpt - deployment/helm/ditto/swaggerui-config/swagger-oidc.js
const OIDC_DISCOVERY_PLACEHOLDER = "__OIDC_DISCOVERY_URL__";
const DITTO_UI_STORAGE_KEY = "ditto-ui-env";

// Restricts where environments may be loaded from - they contain the OIDC provider configuration,
// so loading them from an arbitrary URL would let a crafted link hijack the user's login.
const UI_CONFIG_PATH = "ui-config.json";
const ANY_ORIGIN = "*";
const BLOCKED_PATH_SEGMENTS = ["api", "ws"];

async function loadAllowedOrigins() {
    try {
        const response = await fetch(UI_CONFIG_PATH, { mode: "same-origin", cache: "no-cache" });
        if (!response.ok) {
            return [];
        }
        const json = await response.json();
        const allowedOrigins = json && json.environmentsURL && json.environmentsURL.allowedOrigins;
        if (allowedOrigins === undefined) {
            return [];
        }
        if (!Array.isArray(allowedOrigins) || !allowedOrigins.every((o) => typeof o === "string")) {
            throw new Error("\"environmentsURL.allowedOrigins\" must be an array of strings");
        }
        return allowedOrigins;
    } catch (e) {
        console.warn("SwaggerOidc: Invalid or unavailable UI configuration in", UI_CONFIG_PATH, "- using defaults", e);
        return [];
    }
}

Source: GitHub Commit 71061f0. The patch introduces an allowlist of origins loaded from a same-origin ui-config.json and blocks dangerous path segments.

Detection Methods for CVE-2026-107503

Indicators of Compromise

HTTP referrers or access logs on the Ditto UI containing an environmentsURL query parameter pointing to an external, unexpected origin.
Browser localStorage entries under the ditto-ui-env key referencing OIDC authorities or api_uri values that differ from the organization's configured identity provider or API host.
OIDC provider logs showing authorization code issuance for Ditto UI sessions followed by token exchanges from unexpected IP addresses or user agents.

Detection Strategies

Inspect reverse proxy or CDN logs for inbound requests to the Ditto Explorer UI carrying an environmentsURL query string, and alert on values whose origin is not on an internal allowlist.
Correlate identity provider authorization events with the originating client; mismatches between the Ditto callback origin and the token redemption endpoint indicate an active hijack.
Monitor for unusual bearer token usage patterns against the Ditto API from source IPs that do not match known administrator workstations.

Monitoring Recommendations

Enable verbose access logging on the ingress serving the Ditto UI and forward logs to a central analytics platform for query parameter inspection.
Audit refresh token issuance rates at the OIDC provider and alert on anomalies tied to Ditto client IDs.
Review persisted browser configuration during user support sessions, specifically the ditto-ui-envlocalStorage key.

How to Mitigate CVE-2026-107503

Immediate Actions Required

Upgrade Eclipse Ditto Explorer UI to version 3.8.14 or 3.9.8, which restrict environmentsURL loading to allowlisted origins.
Instruct users to clear localStorage for the Ditto UI origin to purge any attacker-persisted configuration.
Revoke and reissue OIDC refresh tokens for all Ditto UI users who may have followed suspicious links.

Patch Information

The issue is fixed in Eclipse Ditto 3.8.14 and 3.9.8. Patch details are available in the Eclipse Ditto Release Notes 3.8.14, the Eclipse Ditto Release Notes 3.9.8, and the GitHub Security Advisory GHSA-8767. The fix is implemented across commits 71061f0, d4e51ba, and ee65b8c.

Workarounds

Deploy a reverse proxy rule that strips or rejects requests containing the environmentsURL query parameter on the Ditto UI route.
Restrict access to the Ditto Explorer UI and Swagger UI to internal networks or VPN users until the upgrade is applied.
Disable the Swagger UI OIDC integration in Helm or Docker Compose deployments if it is not operationally required.

bash

# Example nginx rule to drop the vulnerable query parameter
location /ditto-ui/ {
    if ($arg_environmentsURL) {
        return 400 "environmentsURL parameter not permitted";
    }
    proxy_pass http://ditto-ui-upstream;
}