Java: detect command injection through delegating launchers by Copilot · Pull Request #22818 · github/codeql

Copilot · 2026-10-14T10:33:06Z

isSafeCommandArgument treated non-first arguments as safe whenever the executable was not a recognized shell. Delegating launchers could therefore execute attacker-controlled arguments without producing a command-line injection alert.

Detection
- Distinguish delegating launchers from shells.
- Recognize env, sudo, xargs, chroot, nice, nohup, setsid, stdbuf, and timeout.
- Apply detection to array literals, mutable arrays, and command lists.
Coverage
- Add an alert case for each recognized launcher.
- Preserve safe handling for non-delegating commands such as cp.

Runtime.getRuntime().exec(new String[]{"env", userControlledInput});

+ */
+private predicate isDelegatingLauncher(Expr ex) {
+  exists(string cmd | cmd = ex.(StringLiteral).getValue() |
+    cmd.regexpMatch("(.*/)?(chroot|env|nice|nohup|setsid|stdbuf|sudo|timeout|xargs)$")


owen-mc · 2026-10-14T10:57:42Z

    i > 0 and
-    not isShell(ai.getInit(0))
+    not isShell(ai.getInit(0)) and
+    not isDelegatingLauncher(ai.getInit(0))


The new check disables sanitization for every argument after a launcher. For example:

new ProcessBuilder(new String[]{"env", "/bin/cp", userInput, "/tmp/destination"});

This now produces java/command-line-injection, although userInput remains a discrete argument to the fixed /bin/cp executable. This contradicts the safe direct-cp behavior tested at Test.java:48 and introduces false positives into a high-precision query.

Make launcher handling position-aware: flag the operand selecting the delegated command, then preserve normal safe-argument handling once a fixed non-shell command is known. Add GOOD cases for array literals, lists, and mutable arrays.

owen-mc · 2026-10-14T10:58:28Z

+ */
+private predicate isDelegatingLauncher(Expr ex) {
+  exists(string cmd | cmd = ex.(StringLiteral).getValue() |
+    cmd.regexpMatch("(.*/)?(chroot|env|nice|nohup|setsid|stdbuf|sudo|timeout|xargs)$")


Common launchers such as flock, su, runuser, doas, and time remain unrecognized. For example, taint in {"flock", "/tmp/lock", userInput} is still sanitized even though userInput selects the executed command. This matches the existing unresolved review thread.

owen-mc · 2026-10-14T11:02:09Z

@copilot Please address the three comments on this PR.

Copilot · 2026-10-14T11:45:00Z

@copilot Please address the three comments on this PR.

Addressed all three comments in edb67fe and 866d93b. Launcher handling now preserves safe arguments after fixed non-shell commands, recognizes the missing wrappers, and includes GOOD cases for literals, lists, and mutable arrays. Added safeguards and regressions for unresolved commands and mutated aliases. All four CWE-078 tests pass; final read-only review found no issues. The automated security scan was skipped because its database was too large.

Copilot

Note

Copilot was unable to run its full agentic suite in this review.

Copilot review overview

6 open findings

This forall quantifies SsaDefinition def but then unconditionally casts def to… · New
exists(...) is used with an expression (exists(this.getArgument(...))), which is not valid QL… · New
commandOperand re-binds the launcher parameter using this.getFixedArgument(_), which can… · New
exists(...) is used with an expression (exists(this.getArgument(...))), which is not valid QL… · New
isShell accounts for Windows-style .exe suffixes, but isDelegatingLauncher does not. This… · New
unknownIndex[arg.length()] can throw ArrayIndexOutOfBoundsException for most inputs (since the… · New

What changed in this PR

Updates the Java CWE-078 CodeQL modeling and tests to better distinguish delegating “launcher” executables (for example env, sudo, timeout) from shells, improving command-injection and relative-path detection accuracy.

Changes:

Extend isSafeCommandArgument to handle delegating launchers by analyzing fixed command prefixes across arrays/lists/mutable arrays.
Add new test cases covering launcher delegation scenarios and update expected query outputs accordingly.
Introduce new argument-sequence abstraction (CommandArguments) and supporting utilities for alias/escape tracking.

File	Description
java/ql/test/query-tests/security/CWE-078/Test.java	Adds new ProcessBuilder test cases for delegating launchers, argument mutation/aliasing, and fixed-vs-tainted scenarios.
java/ql/test/query-tests/security/CWE-078/ExecTainted.expected	Updates expected taint-tracking results to include new test cases and shifted line numbers.
java/ql/test/query-tests/security/CWE-078/ExecRelative.expected	Updates expected relative-path command results for newly added launcher cases and shifted line numbers.
java/ql/lib/semmle/code/java/security/CommandArguments.qll	Implements launcher-aware safe-argument logic, including prefix inspection and container escape tracking.

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+    launcher = this.getFixedArgument(_).regexpCapture("(.*/)?([^/]+)", 2) and
+    options = [true, false] and
+    exists(Expr arg | arg = this.getArgument(index) |
+      (options = false or not this.getFixedArgument(index).matches("-%")) and
+      not (launcher = "env" and this.getFixedArgument(index).matches("%=%")) and
+      result = index
+      or
+      options = true and
+      this.getFixedArgument(index) = "--" and
+      result = this.commandOperand(launcher, index + 1, false)
+      or
+      options = true and
+      exists(int width |
+        launcherOption(launcher, this.getFixedArgument(index), width) and
+        (width = 1 or exists(this.getArgument(index + 1))) and
+        result = this.commandOperand(launcher, index + width, true)
+      )
+      or
+      launcher = "env" and
+      this.getFixedArgument(index).matches("%=%") and
+      result = this.commandOperand(launcher, index + 1, options)


owen-mc · 2026-10-16T09:59:07Z

@copilot Address review comments.

Copilot · 2026-10-16T10:02:50Z

@copilot Address review comments.

Addressed in 8f39336. Fixed the launcher operand binding and review findings, added .exe launcher coverage, and made the dynamic array index safe.

Document supported simple forms and known limitations with inline expectations. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Recognize fixed command positions without parsing launcher options. Only sanitize later arguments when the delegated command is one unchanged string literal. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI assigned Copilot and owen-mc Oct 14, 2026

Copilot started work on behalf of owen-mc October 14, 2026 10:33

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Copilot AI changed the title ~~[WIP] Fix isSafeCommandArgument to account for delegating launchers~~ Java: detect command injection through delegating launchers Oct 14, 2026

Copilot finished work on behalf of owen-mc October 14, 2026 10:42

Copilot AI requested a review from owen-mc October 14, 2026 10:42

github-advanced-security AI found potential problems Oct 14, 2026

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Comment thread java/ql/lib/semmle/code/java/security/CommandArguments.qll Outdated

*/

private predicate isDelegatingLauncher(Expr ex) {

exists(string cmd | cmd = ex.(StringLiteral).getValue() |

cmd.regexpMatch("(.*/)?(chroot|env|nice|nohup|setsid|stdbuf|sudo|timeout|xargs)$")

github-actions Bot added the Java label Oct 14, 2026

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owen-mc requested a max review from Copilot October 14, 2026 12:52

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Copilot stopped reviewing on behalf of owen-mc due to an error October 14, 2026 13:24
An unexpected error occurred. For more details, see the detailed logs in GitHub Actions.

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Copilot started work on behalf of owen-mc October 16, 2026 09:59

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Copilot finished work on behalf of owen-mc October 16, 2026 10:03

owen-mc force-pushed the copilot/fix-is-safe-command-argument branch 3 times, most recently from 4edf3dd to f1d360c Compare October 16, 2026 13:58

Test command injection through delegating launchers

88ef6cf

Document supported simple forms and known limitations with inline expectations. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

owen-mc force-pushed the copilot/fix-is-safe-command-argument branch from f1d360c to f627764 Compare October 16, 2026 16:13

github-advanced-security Bot found potential problems Oct 16, 2026

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Comment thread java/ql/lib/semmle/code/java/security/CommandArguments.qll Fixed

github-actions Bot added the documentation label Oct 16, 2026

owen-mc force-pushed the copilot/fix-is-safe-command-argument branch from f627764 to 78f0ba2 Compare October 16, 2026 18:19

Detect commands passed through simple launchers

8f59bbb

Recognize fixed command positions without parsing launcher options. Only sanitize later arguments when the delegated command is one unchanged string literal. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

owen-mc force-pushed the copilot/fix-is-safe-command-argument branch from 78f0ba2 to 8f59bbb Compare October 16, 2026 18:22

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Java: detect command injection through delegating launchers - #22818

Java: detect command injection through delegating launchers#22818
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