CVE-2026-56328 Overview
CVE-2026-56328 affects Capgo versions prior to 12.128.2. The platform allows multiple public channels for the same app and platform to coexist simultaneously. Unnamed /updates requests that omit defaultChannel implicitly resolve to a single hidden winner channel. An authorized app or channel manager can create an ambiguous default update state. This lets them silently influence which bundle unnamed clients receive, breaking release routing integrity and predictability. The issue maps to [CWE-670: Always-Incorrect Control Flow Implementation]. Capgo assigned the vulnerability through a GitHub Security Advisory and VulnCheck published an independent advisory covering the routing integrity impact.
Critical Impact
An authenticated channel manager can silently redirect unnamed client update requests to an attacker-influenced bundle, undermining release integrity for downstream mobile applications.
Affected Products
- Capgo versions before 12.128.2
- Capgo self-hosted deployments serving /updates endpoints
- Client applications relying on unnamed channel resolution
Discovery Timeline
- 2026-06-30 - CVE-2026-56328 published to NVD
- 2026-07-01 - Last updated in NVD database
Technical Details for CVE-2026-56328
Vulnerability Analysis
Capgo is a live update platform for Capacitor mobile applications. It serves update bundles through a /updates HTTP endpoint. Clients typically pass a defaultChannel parameter to select which release channel they consume. When the parameter is omitted, the server resolves the request to a single winner channel among the public channels registered for the same app and platform. The vulnerability arises because Capgo permits multiple public channels for the same app and platform to be marked as default simultaneously. This ambiguous state produces non-deterministic release routing.
Root Cause
The root cause is a missing uniqueness constraint on the default flag across public channels for a given app and platform. Capgo before 12.128.2 does not enforce that only one public channel can act as the implicit resolution target. Any user with app or channel management privileges can toggle the default flag on additional channels, producing conflicting configuration state. The classification under [CWE-670] reflects the flawed control flow that selects a winner without validating channel exclusivity.
Attack Vector
The attack requires network access to the Capgo control plane and low-privileged authenticated access as an app or channel manager. No user interaction is required on the client side. An authorized manager creates or promotes a rogue public channel and marks it as default. Unnamed /updates requests from mobile clients then resolve to the attacker-controlled channel. Clients silently receive whichever bundle the hidden winner channel advertises. This breaks release predictability without triggering client-side authentication failures. Refer to the GitHub Security Advisory and the VulnCheck Advisory on Integrity Issue for advisory-level details.
Detection Methods for CVE-2026-56328
Indicators of Compromise
- Multiple public channels flagged as default for the same app_id and platform in the Capgo database.
- Unexpected changes to channel default or public flags in Capgo audit logs.
- Client telemetry showing mobile devices receiving bundle versions not associated with the intended release channel.
- /updates responses returning bundle identifiers that do not match the release manager's published channel state.
Detection Strategies
- Query the Capgo channels table for records where public = true and default = true grouped by app_id and platform; any count greater than one indicates ambiguous state.
- Compare deployed bundle checksums on client devices against the expected checksum for the intended default channel.
- Alert on channel configuration changes performed by non-owner accounts using Capgo administrative audit trails.
Monitoring Recommendations
- Continuously monitor Capgo API activity for channel creation and default flag toggles from non-baseline accounts.
- Forward Capgo application and access logs to a centralized analytics platform to correlate channel state changes with /updates response anomalies.
- Track version distribution across the client fleet and flag statistically significant drift from the expected default channel bundle.
How to Mitigate CVE-2026-56328
Immediate Actions Required
- Upgrade Capgo to version 12.128.2 or later, which enforces channel default uniqueness per app and platform.
- Audit all existing public channels and reduce the default flag to a single channel per app and platform combination.
- Review the roster of app and channel manager accounts and revoke privileges that are no longer required.
- Rotate API keys used by channel manager accounts if unauthorized configuration changes are suspected.
Patch Information
Capgo addressed the vulnerability in version 12.128.2. The fix enforces that only one public channel per app and platform can serve as the implicit resolution target for unnamed /updates requests. Deployment details are described in the GitHub Security Advisory.
Workarounds
- Require all clients to pass an explicit defaultChannel parameter on every /updates request until the patch is applied.
- Manually enforce single-default state by disabling the default flag on all but one public channel per app and platform.
- Restrict channel manager role assignments to a minimal set of trusted operators pending upgrade.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
