fix(grep): prevent command-line option injection by passing search patterns with explicit -e delimiter by zainnadeem786 · Pull Request #29536 · google-gemini/gemini-cli

zainnadeem786 · 2026-09-28T08:35:52Z

Summary

This PR hardens the local grep execution module in packages/core/src/tools/grep.ts against Command-Line Option / Argument Injection (CWE-88) by enforcing strict argument separation using the explicit pattern terminator (-e) for both git grep and system grep pipelines.

Problem / Vulnerability Addressed

When constructing search queries, both git grep and system grep previously appended user-supplied or workspace-derived search patterns directly as raw positional arguments:

gitArgs = ['grep', '--untracked', '-n', '-E', '--ignore-case', pattern]
grepArgs.push(pattern)

Because POSIX and GNU command-line parsers process arguments sequentially from left to right, any token beginning with a hyphen (- or --) is interpreted as a command-line flag or option rather than a literal search string.

Impact:

Command Behavior Alteration / Flag Injection: Attackers or untrusted workspaces containing files or search inputs starting with hyphens (e.g., -v, --max-count) could force the underlying tool to misinterpret inputs as flags, altering search output or triggering inverted matches.
Denial of Service (DoS): Passing invalid flag structures (such as --max-count without a trailing integer value) caused the underlying subprocess to crash with fatal errors (fatal: option '--max-count' requires a value), disrupting the active CLI session.
Defense-in-Depth Violation: Failing to isolate positional match patterns from command option parsers violated secure subprocess spawning guidelines.

Solution & Key Changes

Explicit -e Delimiter Enforcement:
- Updated git grep command building to push -e immediately before the search pattern:
```
gitArgs.push('-e', pattern);
```
- Updated system grep command building to prepend -e before the pattern:
```
grepArgs.push('-e', pattern);
```
Comprehensive Unit Testing:
- Added robust unit test cases in packages/core/src/tools/grep.test.ts validating that leading-hyphen search patterns (e.g., -v and --flag) are safely preceded by the -e flag in spawned arguments.

Test Verification

Core grep test suite (grep.test.ts): 35 / 35 tests passed (100%)
Linter & Typecheck: Clean (0 errors, 0 warnings)

Relates to #29627

…patterns with -e

github-actions · 2026-09-28T08:36:06Z

📊 PR Size: size/M

Lines changed: 87
Additions: +78
Deletions: -9
Files changed: 2

github-actions · 2026-09-28T08:37:22Z

🛑 Action Required: Evaluation Approval

Steering changes have been detected in this PR. To prevent regressions, a maintainer must approve the evaluation run before this PR can be merged.

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Go to the Workflow Run Summary.
Click the yellow 'Review deployments' button.
Select the 'eval-gate' environment and click 'Approve'.

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gemini-code-assist · 2026-09-28T08:38:47Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a security vulnerability in the grep execution module where user-provided search patterns could be misinterpreted as command-line flags. By enforcing the use of the '-e' pattern terminator, the system now ensures that all search inputs are treated as positional arguments, significantly improving the robustness and security of the subprocess execution logic.

Highlights

Security Hardening: Implemented the use of the explicit '-e' delimiter for both 'git grep' and system 'grep' commands to prevent command-line option injection (CWE-88).
Vulnerability Mitigation: Ensured that search patterns starting with hyphens are treated as literal strings rather than command flags, preventing potential behavior alteration or subprocess crashes.
Testing: Added comprehensive unit tests to verify that leading-hyphen patterns are correctly isolated with the '-e' flag in both 'git' and 'system' grep execution paths.

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gemini-code-assist

Code Review

This pull request modifies the grep tool to safely handle patterns with leading hyphens by prepending them with the -e flag in both system grep and git grep executions, and adds corresponding unit tests. The review feedback recommends validating and trimming the search pattern to prevent performance issues from whitespace-only inputs, clearing the execStreaming mock in tests to avoid state leakage, and using synchronous filesystem methods for test setup to enhance readability.

…ertions

zainnadeem786 · 2026-09-28T08:56:48Z

@gemini-code-assist review

gemini-code-assist

Code Review

This pull request improves the grep tool by validating that the search pattern is not empty or whitespace-only, and by passing the -e flag before the pattern in both git grep and system grep commands to safely handle leading hyphens. It also adds corresponding unit tests. The review feedback recommends avoiding monkey-patching node:fs/promises in the test file, suggesting instead to import and use mkdirSync directly from node:fs to prevent potential runtime errors in strict ES module environments.

…atching

gemini-cli · 2026-10-06T01:52:46Z

Hi there! Thank you for your interest in contributing to Gemini CLI.

To ensure we maintain high code quality and focus on our prioritized roadmap, we only guarantee review and consideration of pull requests for issues that are explicitly labeled as 'help wanted'.

This PR will be closed in 7 days if it remains without that designation. We encourage you to find and contribute to existing 'help wanted' issues in our backlog! Thank you for your understanding.

zainnadeem786 · 2026-10-06T08:08:47Z

Hi team, just following up on this security hardening PR (#29536). It has already received an approving review from @svessebror-maker. Could a maintainer please help add the appropriate label or merge this in before the 7-day automated closure window? Thank you!

fix(grep): prevent command-line option injection by prefixing search …

08a4415

…patterns with -e

zainnadeem786 requested a review from a team as a code owner September 28, 2026 08:35

github-actions Bot added the size/m A medium sized PR label Sep 28, 2026

gemini-cli Bot added the status/need-issue Pull requests that need to have an associated issue. label Sep 28, 2026

zainnadeem786 had a problem deploying to eval-gate September 28, 2026 08:37 — with GitHub Actions Error

gemini-code-assist Bot reviewed Sep 28, 2026

View reviewed changes

Comment thread packages/core/src/tools/grep.ts

Comment thread packages/core/src/tools/grep.test.ts

Comment thread packages/core/src/tools/grep.test.ts

fix(grep): add whitespace pattern validation and harden unit test ass…

cd812d7

…ertions

zainnadeem786 had a problem deploying to eval-gate September 28, 2026 08:55 — with GitHub Actions Error

gemini-code-assist Bot reviewed Sep 28, 2026

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Comment thread packages/core/src/tools/grep.test.ts Outdated

Comment thread packages/core/src/tools/grep.test.ts Outdated

fix(test): import mkdirSync directly from node:fs instead of monkey-p…

08975fa

…atching

zainnadeem786 had a problem deploying to eval-gate September 28, 2026 09:06 — with GitHub Actions Error

svessebror-maker approved these changes Sep 28, 2026

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github-actions Bot mentioned this pull request Sep 29, 2026

📊 AI CLI 工具社区动态日报 2026-09-29 litang9/big_model_radar#468

Open

Merge branch 'main' into fix-grep-option-injection

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zainnadeem786 requested a deployment to eval-gate September 29, 2026 04:56 — with GitHub Actions Waiting

github-actions Bot mentioned this pull request Sep 29, 2026

📊 AI CLI 工具社区动态日报 2026-09-29 96loveslife/big_model_radar#564

Open

zainnadeem786 mentioned this pull request Oct 4, 2026

[Bug] Command-line option injection vulnerability in grep tool via leading-hyphen search patterns #29627

Open

gemini-cli Bot added area/security Issues related to security and removed status/need-issue Pull requests that need to have an associated issue. labels Oct 4, 2026

github-actions Bot mentioned this pull request Oct 4, 2026

📊 AI CLI 工具社区动态日报 2026-10-05 litang9/big_model_radar#498

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gemini-cli Bot added the priority/p2 Important but can be addressed in a future release. label Oct 5, 2026

github-actions Bot mentioned this pull request Oct 6, 2026

📊 AI CLI 工具社区动态日报 2026-10-06 litang9/big_model_radar#503

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gemini-cli Bot added the status/pr-nudge-sent label Oct 6, 2026

github-actions Bot mentioned this pull request Oct 6, 2026

📊 AI CLI 工具社区动态日报 2026-10-06 96loveslife/big_model_radar#596

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fix(grep): prevent command-line option injection by passing search patterns with explicit -e delimiter - #29536

fix(grep): prevent command-line option injection by passing search patterns with explicit -e delimiter#29536
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