CVE-2019-25766: Renovate Token Disclosure Vulnerability

CVE-2019-25766 Overview

CVE-2019-25766 is an information disclosure vulnerability in Renovate, the automated dependency update tool from Mend (formerly WhiteSource). Renovate versions >= 13.87.0 and <= 19.38.6 leak temporary repository tokens into pull request comments when Go Modules update operations fail under certain conditions. Any user with visibility into the affected pull request comments can harvest these exposed tokens and reuse them against the target repository. The issue is categorized under CWE-532: Insertion of Sensitive Information into Log File. Renovate version 19.38.7 remediates the flaw.

Critical Impact
Leaked temporary repository tokens can grant attackers repository-level access to source code and CI/CD pipelines through automated pull requests.

Affected Products

Renovate >= 13.87.0
Renovate <= 19.38.6
Deployments processing Go Modules dependency updates

Discovery Timeline

2026-08-19 - CVE-2019-25766 published to NVD
2026-08-19 - Last updated in NVD database

Technical Details for CVE-2019-25766

Vulnerability Analysis

Renovate scans repositories, detects outdated dependencies, and opens pull requests to update them. During execution, Renovate uses short-lived repository access tokens to authenticate against the source control platform. In affected versions, failure paths in the Go Modules update handler wrote diagnostic output that included these temporary tokens directly into pull request comments.

Anyone with read access to the pull request, including external contributors on public repositories, could view the plaintext credential. An attacker can then reuse the token before it expires to read repository content, push commits, or manipulate the automated update pipeline. The exposure vector requires no authentication against Renovate itself since the leaked comment lives in the target repository.

Root Cause

The root cause is improper sanitization of error output before posting to pull request comments. Renovate's Go Modules update workflow embedded authenticated repository URLs containing tokens into shell command invocations. When the command failed, the raw error text, including the credential-bearing URL, was propagated into the comment body without redaction. This aligns with the CWE-532 classification for sensitive information written to log or diagnostic outputs.

Attack Vector

Exploitation is passive and opportunistic. An attacker monitors pull requests created by the Renovate bot on target repositories, particularly those containing Go modules. When a Go Modules update fails and the bot posts an error comment, the attacker extracts the temporary token from the comment body. The token can then be used to authenticate to the repository's Git host over HTTPS for the duration of its validity. Public repositories and forks with broad visibility present the highest exposure. See the GitHub Security Advisory and the Vulncheck Advisory on Renovate for the vendor description.

Detection Methods for CVE-2019-25766

Indicators of Compromise

Pull request comments authored by the Renovate bot that contain URLs including x-access-token: or embedded credential strings
Go Modules update failure comments referencing go get, go mod, or GOPROXY output with authentication material
Unexpected Git clone or API access using short-lived tokens originating from non-Renovate IP ranges
Repository audit log entries showing token-based access outside of scheduled Renovate runs

Detection Strategies

Scan historical pull request comments across managed repositories for credential patterns using regular expressions targeting bearer tokens and basic-auth URLs
Correlate Renovate execution logs with Git provider audit events to identify token reuse outside expected windows
Alert on any comment body posted by an automation account that matches secret detection signatures

Monitoring Recommendations

Enable Git provider secret scanning for repository comments and issues in addition to code
Continuously monitor Renovate version deployed in self-hosted installations and compare against 19.38.7 or later
Review CI/CD audit trails for anomalous push events or workflow runs triggered outside standard automation identities

How to Mitigate CVE-2019-25766

Immediate Actions Required

Upgrade Renovate to version 19.38.7 or later across all self-hosted and CI-integrated deployments
Rotate any repository access tokens, GitHub App installation tokens, or platform PATs used by Renovate in affected time windows
Audit pull request comments in repositories processed by vulnerable Renovate versions and redact any comments containing tokens
Revoke and reissue Go module proxy credentials if they were referenced in failed update workflows

Patch Information

The maintainers fixed the issue in Renovate 19.38.7. Upgrade instructions and the full advisory are available at the GitHub Security Advisory GHSA-v7x3-7hw7-pcjg. Users of the hosted Mend Renovate service receive the fix automatically. Self-hosted operators must update the container image or npm package.

Workarounds

Disable Go Modules manager in Renovate configuration until upgrade is complete by setting "gomod": { "enabled": false } in renovate.json
Restrict Renovate to private repositories only, limiting comment visibility to trusted collaborators
Configure Renovate to suppress error output in comments where supported, reducing the surface for accidental credential logging

bash

# Configuration example: disable Go Modules manager pending upgrade
{
  "gomod": {
    "enabled": false
  },
  "suppressNotifications": ["artifactErrors"]
}