CVE-2026-55549mediumCWE-79

CVE-2026-55549: medium-severity vulnerability in yamcs

Yamcs: Reflected XSS in the URL of the Authorize Endpoint

Published · Updated

Follow this CVE+ Monitor yamcs+ Monitor org.yamcs:yamcs-core

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

28Vexday Risk Score

Patch soon. It has a working public exploit.

ssvc Attendcvss 6.5epss 1.3%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Affected products
yamcs · yamcs
Related CVEs — yamcs

In the same product, most dangerous first.

CVE-2026-44596MEDIUMYamcs: No Rate Limiting on Authentication EndpointEPSS 2.1%CVE-2026-55552HIGHYamcs: Unauthenticated Directory TraversalEPSS 1.7%CVE-2026-46621CRITICALYamcs: Authenticated Remote Code Execution (RCE) via Jython Algorithm Code InjectionEPSS 1.1%CVE-2026-44632CRITICALYamcs: Server-Side Code Injection (RCE) via Janino Expression Engine in `JavaExprAlgorithmExecutionFactory`EPSS 1.1%CVE-2026-44595MEDIUMYamcs: Unauthorized user enumeration via IAM API endpointsEPSS 1.1%CVE-2026-42568MEDIUMYamcs Vulnerable to LDAP Injection in LdapAuthModuleEPSS 1.0%