CVE-2026-55565

Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs LikeExpression.fillCode_getValueReturn in yamcs-core/src/main/java/org/yamcs/yarch/streamsql/LikeExpression.java inserts an unescaped LIKE pattern into Java source compiled by Expression.getCompiledExpression through SimpleCompiler.cook instead of applying ValueExpression.escapeJavaString. The pattern can originate from POST /api/archive/{instance}:executeSql, POST /api/archive/{instance}:streamSql, POST /api/archive/{instance}/tables/{table}:readRows, GET /api/archive/{instance}/events, or activity searches, including paths available with ReadTables, ReadEvents, or ReadActivities. A quote in the pattern can inject Java that runs as the Yamcs server process. This issue is fixed in versions 5.12.8 and 5.13.2.

Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs LikeExpression.fillCode_getValueReturn in yamcs-core/src/main/java/org/yamcs/yarch/streamsql/LikeExpression.java inserts an unescaped LIKE pattern into Java source compiled by Expression.getCompiledExpression through SimpleCompiler.cook instead of applying ValueExpression.escapeJavaString. The pattern can originate from POST /api/archive/{instance}:executeSql, POST /api/archive/{instance}:streamSql, POST /api/archive/{instance}/tables/{table}:readRows, GET /api/archive/{instance}/events, or activity searches, including paths available with ReadTables, ReadEvents, or ReadActivities. A quote in the pattern can inject Java that runs as the Yamcs server process. This issue is fixed in versions 5.12.8 and 5.13.2.

Summary

Yamcs compiles StreamSQL query expressions to Java at runtime with Janino. The LIKE operator inserts the user-supplied pattern into the generated Java unescaped, inside a "..." literal, so a pattern containing " breaks out and injects arbitrary Java (e.g. a static{} block that runs an OS command when the compiled filter class loads). Result: RCE as the OS user running Yamcs.

The pattern is embedded raw whether it comes from a SQL string literal or a bound ? argument, so the sink is reachable from any endpoint that builds a LIKE from user input, at routine read-only privileges, not just executeSql:

• POST /api/archive/{instance}:executeSql and :streamSql (privilege ControlArchiving)
• POST /api/archive/{instance}/tables/{table}:readRows via the query field (privilege ReadTables)
• GET /api/archive/{instance}/events?q= and the event export/stream variants (privilege ReadEvents)
• listActivities q (privilege ReadActivities)

The Events page search box feeds q directly.

Independent of the May-2026 algorithm-override RCEs (CVE-2026-46562/46621/44632): it needs none of ChangeMissionDatabase and is not affected by the overrideAlgorithmsEnabled gate.

Details

• Sink: Expression#getCompiledExpression compiles generated source with SimpleCompiler.cook(...) (Expression.java:205) and instantiates it (Expression.java:213) at stream prep, before any tuple flows.
• Injection: LikeExpression#fillCode_getValueReturn (LikeExpression.java:26) appends likeClause.pattern raw into Utils.like(<col>, "<pattern>"). The safe sibling ValueExpression escapes literals via escapeJavaString() (ValueExpression.java:82-85); a review of all 35 streamsql code-generators found LikeExpression to be the only unescaped one.
• Grammar: S_STRING = "'" (~["'"])* "'" (StreamSql.jj:222) allows "; getNonEscapedString (StreamSql.jj:36) does not escape " or \.
• Reachability: TableApi#executeSql (TableApi.java:399) checks only ControlArchiving, then passes the raw statement to ydb.createStatement(...). No SecurityManager or Janino sandbox is configured, so the compiled code can call Runtime/ProcessBuilder. :streamSql (TableApi.java:447) is equally affected.
• The sink is reachable from several lower-privilege endpoints, not just executeSql. A LIKE pattern is embedded raw whether it comes from a SQL literal or a bound ? argument (nextArgAsString -> likeClause.pattern), so any endpoint building ... LIKE ? with attacker input also reaches it:
  • POST .../tables/{table}:readRows (TableApi.java:276, privilege ReadTables): the query and cols request fields are concatenated raw into the executed StreamSQL (sqlb.where(request.getQuery())). Verified RCE.
  • GET .../events?q= (listEvents, EventsApi.java:79/109) and exportEvents/streamEvents (EventsApi.java:290/344), privilege ReadEvents: body.message like ? with "%"+q+"%". Verified RCE.
  • listActivities (ActivitiesApi.java:86/113), privilege ReadActivities: detail like ? with "%"+q+"%". ReadTables/ReadEvents/ReadActivities are routine read-only permissions. The single escapeJavaString fix below closes all of these (one sink). The raw readRows WHERE/cols concatenation is an additional StreamSQL-injection that should be fixed independently (validate cols, do not accept a free-form query at ReadTables).

Proof of Concept

Against a Yamcs server with security enabled (default HTTP port 8090), as a user holding only ControlArchiving.

BASE=http://<host>:8090
INSTANCE=<instance>

# 1. Get a token for a ControlArchiving user.
TOK=$(curl -s -X POST "$BASE/auth/token" \
  -d 'grant_type=password&username=USER&password=PASS' \
  | python3 -c 'import sys,json;print(json.load(sys.stdin)["access_token"])')

# 2. Create a table with a string column.
curl -s -X POST "$BASE/api/archive/$INSTANCE:executeSql" \
  -H "Authorization:…

Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs LikeExpression.fillCode_getValueReturn in yamcs-core/src/main/java/org/yamcs/yarch/streamsql/LikeExpression.java inserts an unescaped LIKE pattern into Java source compiled by Expression.getCompiledExpression through SimpleCompiler.cook instead of applying ValueExpression.escapeJavaString. The pattern can originate from POST /api/archive/{instance}:executeSql, POST /api/archive/{instance}:streamSql, POST /api/archive/{instance}/tables/{table}:readRows, GET /api/archive/{instance}/events, or activity searches, including paths available with ReadTables, ReadEvents, or ReadActivities. A quote in the pattern can inject Java that runs as the Yamcs server process. This issue is fixed in versions 5.12.8 and 5.13.2.

Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs LikeExpression.fillCode_getValueReturn in yamcs-core/src/main/java/org/yamcs/yarch/streamsql/LikeExpression.java inserts an unescaped LIKE pattern into Java source compiled by Expression.getCompiledExpression through SimpleCompiler.cook instead of applying ValueExpression.escapeJavaString. The pattern can originate from POST /api/archive/{instance}:executeSql, POST /api/archive/{instance}:streamSql, POST /api/archive/{instance}/tables/{table}:readRows, GET /api/archive/{instance}/events, or activity searches, including paths available with ReadTables, ReadEvents, or ReadActivities. A quote in the pattern can inject Java that runs as the Yamcs server process. This issue is fixed in versions 5.12.8 and 5.13.2.

Summary

Yamcs compiles StreamSQL query expressions to Java at runtime with Janino. The LIKE operator inserts the user-supplied pattern into the generated Java unescaped, inside a "..." literal, so a pattern containing " breaks out and injects arbitrary Java (e.g. a static{} block that runs an OS command when the compiled filter class loads). Result: RCE as the OS user running Yamcs.

The pattern is embedded raw whether it comes from a SQL string literal or a bound ? argument, so the sink is reachable from any endpoint that builds a LIKE from user input, at routine read-only privileges, not just executeSql:

• POST /api/archive/{instance}:executeSql and :streamSql (privilege ControlArchiving)
• POST /api/archive/{instance}/tables/{table}:readRows via the query field (privilege ReadTables)
• GET /api/archive/{instance}/events?q= and the event export/stream variants (privilege ReadEvents)
• listActivities q (privilege ReadActivities)

The Events page search box feeds q directly.

Independent of the May-2026 algorithm-override RCEs (CVE-2026-46562/46621/44632): it needs none of ChangeMissionDatabase and is not affected by the overrideAlgorithmsEnabled gate.

Details

• Sink: Expression#getCompiledExpression compiles generated source with SimpleCompiler.cook(...) (Expression.java:205) and instantiates it (Expression.java:213) at stream prep, before any tuple flows.
• Injection: LikeExpression#fillCode_getValueReturn (LikeExpression.java:26) appends likeClause.pattern raw into Utils.like(<col>, "<pattern>"). The safe sibling ValueExpression escapes literals via escapeJavaString() (ValueExpression.java:82-85); a review of all 35 streamsql code-generators found LikeExpression to be the only unescaped one.
• Grammar: S_STRING = "'" (~["'"])* "'" (StreamSql.jj:222) allows "; getNonEscapedString (StreamSql.jj:36) does not escape " or \.
• Reachability: TableApi#executeSql (TableApi.java:399) checks only ControlArchiving, then passes the raw statement to ydb.createStatement(...). No SecurityManager or Janino sandbox is configured, so the compiled code can call Runtime/ProcessBuilder. :streamSql (TableApi.java:447) is equally affected.
• The sink is reachable from several lower-privilege endpoints, not just executeSql. A LIKE pattern is embedded raw whether it comes from a SQL literal or a bound ? argument (nextArgAsString -> likeClause.pattern), so any endpoint building ... LIKE ? with attacker input also reaches it:
  • POST .../tables/{table}:readRows (TableApi.java:276, privilege ReadTables): the query and cols request fields are concatenated raw into the executed StreamSQL (sqlb.where(request.getQuery())). Verified RCE.
  • GET .../events?q= (listEvents, EventsApi.java:79/109) and exportEvents/streamEvents (EventsApi.java:290/344), privilege ReadEvents: body.message like ? with "%"+q+"%". Verified RCE.
  • listActivities (ActivitiesApi.java:86/113), privilege ReadActivities: detail like ? with "%"+q+"%". ReadTables/ReadEvents/ReadActivities are routine read-only permissions. The single escapeJavaString fix below closes all of these (one sink). The raw readRows WHERE/cols concatenation is an additional StreamSQL-injection that should be fixed independently (validate cols, do not accept a free-form query at ReadTables).

Proof of Concept

Against a Yamcs server with security enabled (default HTTP port 8090), as a user holding only ControlArchiving.

BASE=http://<host>:8090
INSTANCE=<instance>

# 1. Get a token for a ControlArchiving user.
TOK=$(curl -s -X POST "$BASE/auth/token" \
  -d 'grant_type=password&username=USER&password=PASS' \
  | python3 -c 'import sys,json;print(json.load(sys.stdin)["access_token"])')

# 2. Create a table with a string column.
curl -s -X POST "$BASE/api/archive/$INSTANCE:executeSql" \
  -H "Authorization:…