CVE-2026-55549
Description
Yamcs is a mission control framework. Prior to 5.9.4, Yamcs reflects an attacker-controlled redirect_uri parameter from GET /auth/authorize into yamcs-core/src/main/resources/auth/templates/authorize.html without adequate HTML escaping by yamcs-core/src/main/java/org/yamcs/http/auth/AuthHandler.java and yamcs-core/src/main/java/org/yamcs/http/HandlerContext.java. A crafted authorization URL can execute JavaScript when opened by a Yamcs user. The script can access browser-held authentication material and transmit it to an attacker, enabling account compromise. This issue is fixed in version 5.9.4.
How to fix
- org.yamcs:yamcs-core5.9.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| org.yamcs:yamcs-coreMaven | v < 5.9.4 | 5.9.4 |
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