fix(security): cap Retry-After sleep and sanitize mimeType in uploads by anshul-garg27 · Pull Request #448 · googleworkspace/cli

anshul-garg27 · 2026-03-12T21:31:58Z

Summary

Two security hardening fixes for agent-facing attack surfaces:

1. Cap `Retry-After` sleep to 60 seconds (Critical)

A hostile or compromised API server can return Retry-After: 4294967295 in a 429 response, causing the CLI process to sleep for ~136 billion years. This is a denial-of-service vector, especially dangerous in unattended AI agent workflows where the process runs without human supervision.

Fix: Add .min(60) cap on the parsed Retry-After value in send_with_retry().

2. Sanitize `mimeType` in multipart upload headers (High)

The user-supplied mimeType field from --json body metadata is embedded directly into a MIME Content-Type header:

Content-Type: {media_mime}\r\n\r\n

A crafted mimeType like text/plain\r\nX-Injected: malicious could inject arbitrary MIME headers into the outbound multipart request body.

Fix: Strip \r and \n characters from media_mime before header construction.

Test plan

Added test verifying retry cap clamps large values to 60
Added test verifying normal values pass through unchanged
Existing client and executor tests continue to pass

changeset-bot · 2026-03-12T21:32:02Z

🦋 Changeset detected

Latest commit: bb77df7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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@googleworkspace/cli	Patch

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gemini-code-assist · 2026-03-12T21:32:16Z

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 introduces two critical security enhancements to the CLI's agent-facing attack surfaces. It addresses a potential denial-of-service vulnerability by capping Retry-After sleep durations and mitigates a header injection risk by sanitizing user-provided mimeType values during multipart uploads. These changes improve the robustness and security of the application, especially in automated AI agent workflows.

Highlights

Retry-After Sleep Cap: Implemented a 60-second cap on the Retry-After header value to prevent denial-of-service attacks where a malicious server could cause the CLI process to sleep indefinitely, especially in AI agent workflows.
mimeType Sanitization: Stripped carriage return and newline characters from user-supplied mimeType values in multipart upload headers to prevent MIME header injection vulnerabilities.

Changelog

.changeset/fix-retry-after-and-mime-injection.md
- Added a new changeset file documenting the security fixes for Retry-After and mimeType sanitization.
src/client.rs
- Introduced a MAX_RETRY_DELAY_SECS constant set to 60 seconds.
- Applied a .min(MAX_RETRY_DELAY_SECS) cap to the parsed Retry-After header value.
- Added a new test case retry_after_cap_prevents_unbounded_sleep to verify the Retry-After cap functionality.
src/executor.rs
- Modified the build_multipart_body function to filter out carriage return (\r) and newline (\n) characters from the media_mime string before header construction.

Activity

The author added a test to verify the Retry-After cap correctly clamps large values to 60 seconds.
A test was added to confirm that normal Retry-After values below the cap pass through unchanged.
Existing client and executor tests were confirmed to continue passing.

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gemini-code-assist

Code Review

This pull request introduces two important security hardening fixes. The first change caps the Retry-After sleep duration to prevent a potential denial-of-service attack, and the second sanitizes the mimeType in multipart uploads to prevent MIME header injection. The implementations for both fixes are correct. I've added one comment regarding the test for the Retry-After cap to make it more robust.

src/client.rs

googleworkspace-bot · 2026-03-13T06:48:53Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces two important security fixes for denial-of-service and header injection vulnerabilities. The implementations appear correct and effectively address the described issues. My review feedback focuses on improving the test coverage for these security-critical changes. Adding more robust tests will help ensure these fixes are reliable and prevent future regressions.

src/client.rs

src/executor.rs

googleworkspace-bot · 2026-03-13T06:58:10Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces two important security hardening fixes: capping the Retry-After sleep duration to prevent denial-of-service, and sanitizing the mimeType in multipart uploads to prevent header injection. The changes are well-implemented and include relevant tests. My review includes two suggestions for further hardening: one to make the mimeType sanitization more comprehensive by filtering all control characters, and another to prevent a potential integer overflow in the retry delay calculation, making it more robust for future changes.

src/client.rs

src/executor.rs

googleworkspace-bot · 2026-03-13T07:07:31Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces two important security hardening fixes. The first caps the Retry-After sleep duration to prevent a potential denial-of-service attack. The second sanitizes the mimeType in multipart uploads to prevent MIME header injection. The changes are well-implemented and include appropriate tests. I have provided one suggestion to improve the code by avoiding an unnecessary string allocation.

src/client.rs

googleworkspace-bot · 2026-03-13T07:12:15Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces two security hardening fixes: capping the Retry-After sleep duration to prevent a denial-of-service, and sanitizing the mimeType in multipart uploads to prevent header injection. The changes are well-implemented and include relevant tests. I've found one potential issue in the retry logic where a bit shift could panic if the number of retries is significantly increased in the future. I've suggested a more robust implementation to prevent this.

src/client.rs

googleworkspace-bot · 2026-03-13T07:22:21Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces two important security hardening fixes. The first caps the Retry-After sleep duration to 60 seconds to prevent a potential denial-of-service attack, which is implemented cleanly by adding a .min() to the delay calculation. The second fix sanitizes the mimeType field in multipart uploads to prevent header injection by filtering out control characters. Both changes are well-implemented, include corresponding unit tests to verify the fixes, and effectively address the described vulnerabilities.

Two security fixes: 1. Cap Retry-After header value to 60 seconds. A hostile or compromised API server could send Retry-After: 4294967295 to hang the CLI process indefinitely. This is especially dangerous for AI agent workflows where the process runs unattended. 2. Strip CR/LF from user-supplied mimeType before embedding it in the multipart MIME header. A mimeType like "text/plain\r\nX-Evil: injected" could inject arbitrary MIME headers into the upload body.

Extract the constant from inside the function body to module level so it's shared between production code and tests. Use the constant in the test assertion instead of the magic number 60.

Address Gemini review feedback: - Extract retry delay logic into a testable compute_retry_delay() function with 5 focused unit tests covering: large values, small values, missing header, unparseable header, and boundary values - Add unit test for mimeType CRLF sanitization in multipart uploads to verify header injection prevention All 590 tests pass locally.

- Use 1u64 << attempt to prevent potential i32 overflow on large attempt values - Strip all control characters (not just CR/LF) from mimeType to prevent any control char injection in MIME headers

Pass the &str directly from HeaderValue::to_str() to compute_retry_delay instead of cloning into an owned String.

Replace 1u64 << attempt with 2u64.saturating_pow(attempt) to prevent panic if MAX_RETRIES is ever increased beyond 63.

googleworkspace-bot · 2026-03-13T20:32:15Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces two important security hardening fixes: capping the Retry-After sleep duration to prevent denial-of-service, and sanitizing the mimeType in multipart uploads to prevent header injection. The changes are well-implemented and include relevant tests. I've identified a minor edge case in the mimeType sanitization where a user-provided mimeType consisting solely of control characters would result in an empty Content-Type header, and I've suggested a small improvement to handle this.

gemini-code-assist · 2026-03-13T20:34:32Z

src/executor.rs

+    let media_mime: String = media_mime_raw
+        .chars()
+        .filter(|c| !c.is_control())
+        .collect();


After sanitizing media_mime_raw by removing control characters, the resulting media_mime string could be empty (e.g., if the input was just "\r\n"). This would lead to an empty Content-Type header for the media part, which is likely not intended and might be rejected by the server. It would be more robust to fall back to the default "application/octet-stream" if the sanitized string is empty.

Suggested change

let media_mime: String = media_mime_raw

.chars()

.filter(|c| !c.is_control())

.collect();

let mut media_mime: String = media_mime_raw

.chars()

.filter(|c| !c.is_control())

.collect();

if media_mime.is_empty() {

media_mime.push_str("application/octet-stream");

}

good edge case — added a fallback to application/octet-stream if the sanitized mime ends up empty

anshul-garg27 requested a review from jpoehnelt as a code owner March 12, 2026 21:31

googleworkspace-bot added the area: http label Mar 12, 2026

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anshul-garg27 added 6 commits March 14, 2026 02:00

refactor: move MAX_RETRY_DELAY_SECS to module level

6b4e832

Extract the constant from inside the function body to module level so it's shared between production code and tests. Use the constant in the test assertion instead of the magic number 60.

fix: use u64 literal for shift and strip all control chars from mimeType

8f355cc

- Use 1u64 << attempt to prevent potential i32 overflow on large attempt values - Strip all control characters (not just CR/LF) from mimeType to prevent any control char injection in MIME headers

refactor: avoid unnecessary String allocation in retry header parsing

081db71

Pass the &str directly from HeaderValue::to_str() to compute_retry_delay instead of cloning into an owned String.

fix: use saturating_pow for overflow-safe exponential backoff

bb77df7

Replace 1u64 << attempt with 2u64.saturating_pow(attempt) to prevent panic if MAX_RETRIES is ever increased beyond 63.

anshul-garg27 force-pushed the fix/cap-retry-after-sleep branch from 5fd6c34 to bb77df7 Compare March 13, 2026 20:31

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anshul-garg27 commented Mar 12, 2026

Summary

1. Cap Retry-After sleep to 60 seconds (Critical)

2. Sanitize mimeType in multipart upload headers (High)

Test plan

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1. Cap `Retry-After` sleep to 60 seconds (Critical)

2. Sanitize `mimeType` in multipart upload headers (High)

changeset-bot bot commented Mar 12, 2026 •

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