HighVulnerabilityLLM-specific

CVE-2026-54030: LibreChat MCP OAuth token theft through unvalidated resource parameter

Source: NVD(opens in a new tab)
Identifier: CVE-2026-54030
Published: June 25, 2026
Record updated: October 9, 2026

Known exploitation: Not listed in the CISA Known Exploited Vulnerabilities catalog at the last check.
EPSS: 0.2%

Summary

CVE-2026-54030 affects LibreChat before 0.8.5. Its MCP OAuth implementation does not check that the resource parameter from OAuth Protected Resource metadata (RFC 9728) matches the configured MCP server URL. A malicious MCP server can therefore steal access tokens meant for a legitimate server.

Mitigation

Fixed in 0.8.5.

Details

Scores and exploitation

CVSS score: 8(high)
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
Attack vector: network
Attack complexity: high
Privileges required: none
User interaction: required
EPSS: 0.2%Estimated probability that this CVE is exploited in the next 30 days, from the FIRST Exploit Prediction Scoring System. Read on November 10, 2026.
Disclosure date: June 25, 2026

Weaknesses and techniques

Weakness (CWE): CWE-346

Classification

Attack type: Other
Attack sophistication: Moderate
AI component targeted: Plugin
Impact: Confidentiality
Labels: security

How this record was produced

Summaries, mitigations and labels on this page are generated automatically from the source. The linked source is authoritative. The source gives this advisory a description and no title, so the title above is a headline generated from the source text.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-54030

First tracked: June 25, 2026 at 02:11 PM ET, from NVD/CVE Database

Classifier: claude-haiku-5-5, prompt v4

Classifier confidence: 90% (self-assessed)

Topics

Model Context Protocol

Summary

Mitigation

Topics

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