CVE-2026-41488: LangChain OpenAI SSRF bypass via DNS rebinding in image token counting

Summary

LangChain versions prior to 1.1.14 contain a flaw in the langchain-openai package's _url_to_size() helper, which get_num_tokens_from_messages uses for image token counting. The helper validates a URL against SSRF protections, then fetches it in a separate network operation with independent DNS resolution. An attacker-controlled hostname can resolve to a public IP during validation and to a private or localhost IP during the fetch, a TOCTOU / DNS rebinding window.

Mitigation

Fixed in 1.1.14.

Affected packages in the Exposure Registry

Matched by package name and ecosystem. Each entry shows whether the package delegates to a language model and how many tracked packages depend on it.

• langchain-openaiPyPILLM dependency since 2024-01-05 · 29 tracked dependents

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