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CVE-2026-31943— LibreChat has SSRF protection bypass via IPv4-mapped IPv6 normalization in isPrivateIP

Quick assessment

Affected
danny-avila LibreChat
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

LibreChat是LibreChat开源的一个免费、高度可定制的统一 AI 对话平台，能够在一个界面中聚合并运行来自任意厂商的大模型。 LibreChat 0.8.3之前版本存在代码问题漏洞，该漏洞源于packages/api/src/auth/domain.ts中的isPrivateIP函数未能检测十六进制规范化形式的IPv4映射IPv6地址，可能导致任何经过身份验证的用户绕过SSRF保护，使服务器向内部网络资源发出HTTP请求。

CVSS 8.5 · High EPSS 0.30% · P21

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-31943

Vulnerability Information
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Vulnerability Title
LibreChat has SSRF protection bypass via IPv4-mapped IPv6 normalization in isPrivateIP
Source: CVE Program / CVE List V5
Vulnerability Description
LibreChat is a ChatGPT clone with additional features. Prior to version 0.8.3, `isPrivateIP()` in `packages/api/src/auth/domain.ts` fails to detect IPv4-mapped IPv6 addresses in their hex-normalized form, allowing any authenticated user to bypass SSRF protection and make the server issue HTTP requests to internal network resources — including cloud metadata services (e.g., AWS `169.254.169.254`), loopback, and RFC1918 ranges. Version 0.8.3 fixes the issue.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5
Vulnerability Title
LibreChat 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
LibreChat是LibreChat开源的一个免费、高度可定制的统一 AI 对话平台，能够在一个界面中聚合并运行来自任意厂商的大模型。 LibreChat 0.8.3之前版本存在代码问题漏洞，该漏洞源于packages/api/src/auth/domain.ts中的isPrivateIP函数未能检测十六进制规范化形式的IPv4映射IPv6地址，可能导致任何经过身份验证的用户绕过SSRF保护，使服务器向内部网络资源发出HTTP请求。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
danny-avila LibreChat < 0.8.3 -

II. Public POCs for CVE-2026-31943

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III. Intelligence Information for CVE-2026-31943

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Vendor Advisories for CVE-2026-31943 (1)

Same Patch Batch · danny-avila · 2026-03-27 · 4 CVEs total

CVE-2026-31945 7.7 HIGH LibreChat Server-Side Request Forgery using DNS resolution
CVE-2026-31951 6.8 MEDIUM LibreChat's MCP Server Header Injection Enables OAuth Token Theft
CVE-2026-31950 5.3 MEDIUM LibreChat's IDOR in SSE Stream Subscription Allows Reading Other Users' Chats

IV. Related Vulnerabilities

Same product: LibreChat
Same vendor: danny-avila
Same weakness: CWE-918

V. Comments for CVE-2026-31943

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