Cloud Vulnerability DB
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Vulnerability DatabaseCVE-2025-4727
CVE-2025-4727:
JavaScript vulnerability analysis and mitigation
Overview
A vulnerability was discovered in Meteor versions up to 3.2.1, identified as CVE-2025-4727. The issue affects the Object.assign function in the packages/ddp-server/livedata_server.js file, specifically in the handling of the forwardedFor argument. The vulnerability was disclosed in May 2025 and has been classified as problematic, with a CVSS v4.0 base score of 6.3 (MEDIUM) (VulDB).
Technical details
The vulnerability stems from inefficient regular expression complexity in the processing of the x-forwarded-for header within the DDP server component. The issue specifically affects the Session._clientAddress functionality where the manipulation of comma-separated values in the forwardedFor argument can lead to performance issues. The vulnerability has received a CVSS v3.1 base score of 3.7 LOW and has been classified under CWE-1333 (Inefficient Regular Expression Complexity) and CWE-400 (Uncontrolled Resource Consumption) (NVD).
Impact
The vulnerability can lead to inefficient regular expression processing which may result in performance degradation of the affected system. While the vulnerability does not directly compromise data confidentiality or integrity, it could potentially be exploited to cause resource consumption issues, particularly when processing maliciously crafted x-forwarded-for headers (GitHub PR).
Mitigation and workarounds
The vulnerability has been fixed in Meteor version 3.2.2. Users are strongly recommended to upgrade to this version to address the issue. The fix includes enhanced handling of comma-separated values in Session._clientAddress, explicit trimming of IP addresses, and updated validation to ensure exact matching for httpForwardedCount (GitHub Commit).
Community reactions
The vulnerability was initially reported through GitHub issue #13713 and subsequently addressed through pull request #13721. The Meteor development team responded promptly by implementing fixes and releasing a security update. The community has shown appreciation for the quick response and thorough handling of the security issue (GitHub PR).
Additional resources
Source: This report was generated using AI
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