CVE-2026-31944Public exploitNetwork attack vector

Authenticated OAuth token theft via unbound callback

Published Mar 13, 2026 · Updated Mar 13, 2026

Authentication bypass in Danny Avila LibreChat 0.8.2 through 0.8.2-rc3 allows remote authenticated users to steal MCP OAuth tokens. The MCP callback in api/server/routes/mcp.js trusts the cached flow initiator, exchanges the victim's authorization code, and stores the resulting tokens without authenticating the browser or matching its user to that initiator. Exploitation requires a LibreChat account, an OAuth-enabled MCP server, and victim interaction; resulting access is limited to the linked service's granted OAuth scopes.

CVSS severity7.6
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Danny Avila LibreChat 0.8.2 through 0.8.2-rc3 allows remote authenticated users to steal MCP OAuth tokens. The MCP callback in api/server/routes/mcp.js trusts the cached flow initiator, exchanges the victim's authorization code, and stores the resulting tokens without authenticating the browser or matching its user to that initiator. Exploitation requires a LibreChat account, an OAuth-enabled MCP server, and victim interaction; resulting access is limited to the linked service's granted OAuth scopes.

The record

CVE
CVE-2026-31944
Published
Mar 13, 2026
Updated
Mar 13, 2026
Vendor
Danny Avila
Product
LibreChat
Classifications
CWE-306, T1528
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= v0.8.2, <= 0.8.2-rc3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Danny Avila · LibreChatversion=>= v0.8.2, <= 0.8.2-rc3

Published CVSS scores

7.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1528Steal Application Access Token

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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