CVE-2026-85740: CVE-2026-85740: Server-Side Request Forgery (SSRF) Guard Bypass via IPv6 Transition Wrappers in LightRAG

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CVE-2026-85740: Server-Side Request Forgery (SSRF) Guard Bypass via IPv6 Transition Wrappers in LightRAG

Vulnerability ID: CVE-2026-85740
CVSS Score: 7.1
Published: 2026-09-22

A security vulnerability in HKUDS/LightRAG prior to v1.5.5 allows authenticated attackers to bypass the native markdown image downloader guard. The system fails to normalize IPv6 transition wrappers (such as NAT64, IPv4-compatible, and 6to4 blocks) encapsulating internal IPv4 addresses. Python's ipaddress library evaluates these wrappers as globally routable, but hosting environments running NAT64/DNS64 routing decapsulate and route the requests to internal resources.

TL;DR

LightRAG before v1.5.5 is vulnerable to SSRF because its image-download validator fails to inspect IPv4 addresses wrapped in IPv6 transition formats, permitting access to local networks and cloud metadata services.

⚠️ Exploit Status: POC

Technical Details

CWE ID: CWE-918
Attack Vector: Network (AV:N)
Attack Complexity: High (AC:H)
Privileges Required: Low (PR:L)
Scope: Changed (S:C)
Impact: Confidentiality: High, Integrity: Low, Availability: None
Exploit Status: PoC / Non-weaponized
CISA KEV Status: Not Listed

Affected Systems

HKUDS/LightRAG
LightRAG: < 1.5.5 (Fixed in: 1.5.5)

Mitigation Strategies

Upgrade to LightRAG version 1.5.5 or higher.
Implement network egress restrictions for the RAG parsing environment.
Configure IMDSv2 with a strict hop-limit of 1 on host instances.

Remediation Steps:

Identify current LightRAG deployment version.
Update dependency manifest to specify v1.5.5 or later.
Rebuild and redeploy the container or application instance.
Verify outward parser communication is filtered at the network layer.

References

Read the full report for CVE-2026-85740 on our website for more details including interactive diagrams and full exploit analysis.

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