What is the CVSS score of CVE-2026-31943?

CVE-2026-31943 has a CVSS 3.1 base score of 8.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Librechat are affected by CVE-2026-31943?

LibreChat versions before 0.8.3 contain a server-side request forgery (SSRF) vulnerability that allows authenticated users to bypass network access controls and force the application to access…. A patch is available.

How to fix or mitigate CVE-2026-31943?

Within 24 hours: Identify all LibreChat instances and current versions across the environment. Within 7 days: Upgrade LibreChat to version 0.8.3 or later on all affected systems; validate upgrade completion. Within 30 days: Conduct audit of request logs to identify any suspicious internal network access patterns or metadata service queries; review user access permissions to least-privilege model.

Librechat CVE-2026-31943

EUVD-2026-16764 HIGH

Server-Side Request Forgery (SSRF) (CWE-918)

2026-03-27 GitHub_M

SSRF Librechat

8.5

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

8.5 HIGH

AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Updated

Apr 16, 2026 - 06:12 EUVD-patch-fix

executive_summary

Re-analysis Queued

Apr 16, 2026 - 05:29 backfill_euvd_patch

patch_released

Patch available

Apr 16, 2026 - 05:29 EUVD

0.8.3

EUVD ID Assigned

Mar 27, 2026 - 19:45 euvd

EUVD-2026-16764

Analysis Generated

Mar 27, 2026 - 19:45 vuln.today

CVE Published

Mar 27, 2026 - 19:21 nvd

HIGH 8.5

DescriptionGitHub Advisory

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.

AnalysisAI

Server-Side Request Forgery (SSRF) in LibreChat versions prior to 0.8.3 allows authenticated users to bypass IP validation and force the application server to make HTTP requests to internal network resources. The vulnerability stems from improper validation of IPv4-mapped IPv6 addresses in hex-normalized form, enabling access to cloud metadata services (AWS 169.254.169.254), loopback addresses, and RFC1918 private networks. With EPSS data unavailable and no CISA KEV listing, no public exploit identified at time of analysis, though the specific bypass technique (hex-normalized IPv4-mapped IPv6) is well-documented in SSRF research.

Technical ContextAI

The vulnerability exists in the isPrivateIP() function within packages/api/src/auth/domain.ts of LibreChat, an open-source ChatGPT alternative. The function implements SSRF protection by validating IP addresses before allowing HTTP requests, but fails to properly detect IPv4-mapped IPv6 addresses when presented in hex-normalized format (e.g., 0xA9FEA9FE representing 169.254.169.254). IPv4-mapped IPv6 addresses use the format ::ffff:a.b.c.d, but can be obfuscated through various encoding schemes. This represents a classic CWE-918 (Server-Side Request Forgery) implementation flaw where input validation fails to account for alternative IP address representations. The affected product (cpe:2.3:a:danny-avila:librechat) is a Node.js-based application that likely uses user-supplied URLs for legitimate features like web scraping or API integrations, which becomes the attack vector when validation is bypassed.

RemediationAI

Upgrade immediately to LibreChat version 0.8.3 or later, which includes fixes to the isPrivateIP() validation function in packages/api/src/auth/domain.ts to properly detect hex-normalized IPv4-mapped IPv6 addresses. Organizations should verify the update by testing that requests to internal IP addresses in various encoding formats (standard dotted decimal, hex, octal, IPv4-mapped IPv6) are properly blocked. As a defense-in-depth measure pending upgrade, implement network-level controls such as egress filtering to prevent the LibreChat server from accessing cloud metadata endpoints (169.254.169.254, fd00:ec2::254) and internal RFC1918 ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16). Review application logs for suspicious outbound requests to internal IP ranges that may indicate prior exploitation. Consult the GitHub security advisory at https://github.com/danny-avila/LibreChat/security/advisories/GHSA-w5r7-4f94-vp4c for additional vendor-specific guidance and validation steps.