CVE-2026-55443 langchain-ai CVE debrief

Who should care

Developers and security teams using LangChain versions prior to 1.3.9 should be aware of this vulnerability and take immediate action to patch or mitigate the risk. This vulnerability could lead to unauthorized file disclosure, which might be critical for applications handling sensitive data. Security teams should prioritize patching, especially in environments where LangChain is used to process untrusted input or handle sensitive data.

Technical summary

CVE-2026-55443 is caused by multiple LangChain components that do not properly confine resolved paths to their intended root directories. Affected components include a file-search agent middleware, prompt- and chain/agent-configuration loaders, and path-prefix authorization checks. These weaknesses allow attackers to use glob patterns and symlinks to access files outside the configured root directory. The vulnerability is rated with a CVSS score of 5.1 and a medium severity. The CVSS vector is CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N, indicating a local attack vector with high attack complexity and no required privileges or user interaction. The vulnerability leads to high confidentiality impact but no impact on integrity or availability.

Defensive priority

Patching to version 1.3.9 or later is strongly recommended. In the interim, defenders should validate and confine all path inputs, restrict the use of glob patterns and symlinks, and monitor for suspicious file access patterns.

Recommended defensive actions

• Apply the patch by updating LangChain to version 1.3.9 or later.
• Implement additional input validation and path normalization for all path-based inputs.
• Restrict the use of glob patterns and symlinks in untrusted contexts.
• Monitor file access patterns for anomalies that might indicate exploitation attempts.
• Perform thorough inventory checks to identify potentially vulnerable LangChain deployments.
• Consider compensating controls such as Web Application Firewalls (WAFs) to detect and prevent path traversal attacks.

Evidence notes

The CVE and NVD records provide detailed information about the vulnerability, including its CVSS score, affected versions, and patch information. Vendor advisories and patch notes from LangChain are available, offering guidance on mitigation and remediation.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.