CVE-2026-55548: Yamcs: Insecure Direct Object Reference (IDOR) in PacketsApi allows unprivileged users to dump all telemetry packets

Summary The PacketsApi.exportPackets endpoint in Yamcs fails to properly enforce object-level privileges (ReadPacket) when an API request omits specific packet names. As a result, an attacker with a low-privileged account (or any authenticated user with zero privileges) can dump the entire archive of raw telemetry packets for a Yamcs instance. This leads to a massive Information Disclosure of sensitive mission telemetry, completely bypassing the intended Role-Based Access Control (RBAC) model.

Vulnerability Details In yamcs-core/src/main/java/org/yamcs/http/api/PacketsApi.java, the exportPackets method processes requests to export raw packets from the tm (telemetry archive) table.

java @Override public void exportPackets(Context ctx, ExportPacketsRequest request, Observer<HttpBody> observer) { String instance = InstancesApi.verifyInstance(request.getInstance());

Set<String> nameSet = new HashSet<>(request.getNameList()); ctx.checkObjectPrivileges(ObjectPrivilegeType.ReadPacket, nameSet);

SqlBuilder sqlb = new SqlBuilder(XtceTmRecorder.TABLENAME); // ... time filters ...

if (request.getNameCount() > 0) { sqlb.whereColIn("pname", nameSet); } String sql = sqlb.toString(); // ... The method attempts to verify privileges using ctx.checkObjectPrivileges(ObjectPrivilegeType.ReadPacket, nameSet). However, if the request.getNameList() is empty (i.e., the attacker does not specify any packet names to filter by), nameSet is empty. The checkObjectPrivileges method loops over this empty set and successfully passes without throwing a ForbiddenException.

Since request.getNameCount() is 0, no WHERE pname IN (...) filter is added to the SQL query. The resulting sql query becomes a SELECT FROM tm (with optional time filters).

Finally, the query is executed and the results are streamed back to the user: java StreamFactory.stream(instance, sql, sqlb.getQueryArguments(), new StreamSubscriber() {

@Override public void onTuple(Stream stream, Tuple tuple) { if (observer.isCancelled()) { stream.close(); return; }

byte[] raw = (byte[]) tuple.getColumn(StandardTupleDefinitions.TMPACKETCOLUMN); HttpBody body = HttpBody.newBuilder() .setData(ByteString.copyFrom(raw)) .build(); observer.next(body); } // ... Crucially, unlike the streamPackets or exportPacket methods (which explicitly check ctx.user.hasObjectPrivilege for each packet retrieved before returning them), the onTuple handler in exportPackets blindly streams all retrieved packets to the user without any per-row authorization checks.

Thus, a user who possesses no ReadPacket privileges at all can easily bypass authorization and extract all telemetry data from the archive.

Steps to Reproduce 1. Start the Yamcs server (e.g., using the simulation example) with authentication enforced. 2. Log in as a low-privileged user (or use their credentials) who does not have the ReadPacket privilege. 3. Send an HTTP GET request to the export packets endpoint without specifying any name parameters: bash curl -v -u lowprivuser:password "http://localhost:8090/api/archive/simulator:exportPackets" -o dumpedpackets.raw 4. Observe that the server responds with HTTP 200 OK and streams all raw packets to the response, saving them to dumpedpackets.raw. 5. The downloaded file contains raw CCSDS Space Packets (binary telemetry data). 6. Contrast this with an attempt to fetch a specific packet (or calling listPackets for an unauthorized packet), which correctly enforces authorization and rejects the request.

Impact Telemetry packets contain the core mission data, vehicle health status, and sensitive measurements (CCSDS Protocol data). This vulnerability completely breaks the access control model for telemetry data, allowing any authenticated user to exfiltrate all historical telemetry packets from the database. In an aerospace or mission-critical environment, this represents a severe data leak (Massive Information Disclosure) of proprietary or classified spacecraft data.

Remediation Ensure that exportPackets enforces the same per-row privilege checks as streamPackets. Update the onTuple handler to check the user's privileges before emitting each packet:

java @Override public void onTuple(Stream stream, Tuple tuple) { if (observer.isCancelled()) { stream.close(); return; }

// FIX: Retrieve packet name and check authorization String pname = (String) tuple.getColumn(XtceTmRecorder.PNAMECOLUMN); if (ctx.user.hasObjectPrivilege(ObjectPrivilegeType.ReadPacket, pname)) { byte[] raw = (byte[]) tuple.getColumn(StandardTupleDefinitions.TMPACKETCOLUMN); HttpBody body = HttpBody.newBuilder() .setData(ByteString.copyFrom(raw)) .build(); observer.next(body); } }

System Information - Affected Versions: 5.13.0 (Latest Release), 5.12.x, and current master branch. - Tested Revision (master): 309218c651680f79df11a8d0f8628f7033f98a83 - Vulnerability Type: Insecure Direct Object Reference (IDOR) / Logical Authorization Bypass

PoC Images:

- Check version: <img width="1157" height="489" alt="image" src="https://github.com/user-attachments/assets/58608222-b76f-4eb4-8e57-423523062992" />

- Check privilege of user: <img width="1439" height="953" alt="image" src="https://github.com/user-attachments/assets/aa7e55f2-2460-4f24-8b6f-d461d2499a6f" /> <img width="1214" height="224" alt="image" src="https://github.com/user-attachments/assets/e9123ae3-a194-462d-a5ca-2c0b1cc9cc6f" />

- Exploit:

<img width="1728" height="685" alt="image" src="https://github.com/user-attachments/assets/0c7b3099-44d6-4392-bbaa-8e84cc151784" />

<img width="1768" height="797" alt="image" src="https://github.com/user-attachments/assets/df4016a5-d460-4611-a34a-8c0d206edd9c" />