Description
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.
Affected products
langchain: langchain-openai
References1
- github.com/langchain-ai/langchain/security/advisories/GHSA-r7w7… MitigationVendor Advisory
Metrics
- CVSS 3.1
-
3.1
LOW
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N - EPSS — exploit probability
- 0% percentile: 5 · as of 13 November 2026
- CWE
- CWE-918
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.