LangChain — Ssrf (CVE-2026-41488)
Date: 2026-04
Affected: langchain/langchain-openai
Attack vector: ssrf
Category: vulnerability-disclosure
Severity: Low
CVE: CVE-2026-41488
CWE: CWE-918
CVSS: 3.1 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N)

LangChain is a framework for building agents and LLM-powered applications. Prior to 1.1.14, langchain-openai's _url_to_size() helper (used by get_num_tokens_from_messages for image token counting) validated URLs for SSRF protection and then fetched them in a separate network operation with independent DNS resolution. This left a TOCTOU / DNS rebinding window: an attacker-controlled hostname could resolve to a public IP during validation and then to a private/localhost IP during the actual fetch.


Mitigations:

Architectural layers (MAESTRO):