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Low severity2.2NVD Advisory· Published Jun 17, 2026· Updated Jun 17, 2026

Pi Agent: Race condition in Pi auth.json writes could expose stored credentials

CVE-2026-54327

Description

# Pi auth.json writes could briefly expose stored credentials to local users

Pi stored API keys and OAuth credentials in auth.json. A race condition in the file write path could briefly create or rewrite this file with permissions derived from the process umask before tightening the file to owner-only permissions.

Info

The affected credential storage code wrote auth.json and then corrected the file mode in a separate operation. During the interval between those operations, a local user who could read and traverse the Pi agent configuration directory could potentially read the file before its permissions were restricted.

The file can contain API keys, OAuth access tokens, and OAuth refresh tokens for configured providers. The affected behavior was present in the original auth.json credential storage implementation and thus affects both the original @mariozechner/pi-coding-agent package as well as @earendil-works/pi-coding-agent.

Impact

Exploitation requires local access to the same machine and read/traverse access to the victim's Pi agent configuration directory. Users whose ~/.pi/agent directory is private to their account are less exposed. The main impact is disclosure of stored provider credentials, which may allow use of the configured provider accounts according to the privileges of those credentials.

This is not remotely exploitable by itself.

Affected versions

  • Affected: @mariozechner/pi-coding-agent >= 0.28.0, <= 0.73.1
  • Affected: @earendil-works/pi-coding-agent >= 0.74.0, < 0.78.1
  • Patched: @earendil-works/pi-coding-agent >= 0.78.1

The solution

Version 0.78.1 changed the credential storage writes to create auth.json with mode 0600 at open time. The fix applies to initial file creation and credential save paths, including OAuth token refresh writes.

Recommendations

Upgrade to @earendil-works/pi-coding-agent version 0.78.1 or later. Users still on the deprecated @mariozechner/pi-coding-agent package should migrate to the @earendil-works/pi-coding-agent package and install version 0.78.1 or later.

After upgrading, rotate any credentials that may have been exposed on multi-user systems where the Pi agent configuration directory was readable by other local users.

Workarounds

If upgrading immediately is not possible, restrict the Pi agent configuration directory so only the owning user can traverse it, restrict auth.json to owner-only permissions, and run Pi with a restrictive umask such as 077 until the upgrade is complete.

Timeline

  • 2026-05-29: Report received
  • 2026-06-02: Fix committed
  • 2026-06-04: Fixed version released
  • 2026-06-08: Advisory published

Credits

Reported by Paul Urian and Cosmin Alexa of CrowdStrike.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Affected products

2

Patches

Vulnerability mechanics

Root cause

"A TOCTOU race condition where auth.json is written with default umask permissions before being explicitly restricted to owner-only access."

Attack vector

An attacker with local shell access and read/traverse permissions to the victim's `~/.pi/agent` directory can exploit the race window between `writeFileSync` and the subsequent `chmodSync` call. During that interval, `auth.json` is created with permissions derived from the process umask, which may allow the attacker to read the file before it is tightened to owner-only access. The file may contain API keys, OAuth access tokens, and refresh tokens [ref_id=1]. This is not remotely exploitable.

Affected code

The race condition exists in `FileAuthStorageBackend` within `packages/coding-agent/src/core/auth-storage.ts`. The `ensureFileExists`, `withLock`, and `withLockAsync` methods each call `writeFileSync` without specifying a file mode, then separately call `chmodSync` to set mode `0o600`. Between these two calls, the file is readable by other local users according to the process umask.

What the fix does

The patch introduces a constant `AUTH_FILE_WRITE_OPTIONS` that includes `mode: 0o600` and passes it to every `writeFileSync` call that writes `auth.json` [patch_id=6351629]. This ensures the file is created with owner-only permissions atomically at open time, eliminating the window where the file could be readable by other local users. The redundant `chmodSync` calls remain but are no longer necessary for security.

Preconditions

  • authAttacker must have local shell access to the same machine as the victim.
  • configAttacker must have read and traverse permissions on the victim's ~/.pi/agent directory.
  • inputThe race window must be successfully hit between writeFileSync and chmodSync.

Generated on Jun 17, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

4

News mentions

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