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LOW3.7

PYSEC-2026-1509

langchain Server-Side Request Forgery vulnerability

Quick fix

PYSEC-2026-1509 — langchain: upgrade to the fixed version with the command below.

pip install --upgrade 'langchain>=0.1.0'

Details

With the following crawler configuration:

```python from bs4 import BeautifulSoup as Soup

url = "https://example.com" loader = RecursiveUrlLoader( url=url, max_depth=2, extractor=lambda x: Soup(x, "html.parser").text ) docs = loader.load() ```

An attacker in control of the contents of `https://example.com` could place a malicious HTML file in there with links like "https://example.completely.different/my_file.html" and the crawler would proceed to download that file as well even though `prevent_outside=True`.

https://github.com/langchain-ai/langchain/blob/bf0b3cc0b5ade1fb95a5b1b6fa260e99064c2e22/libs/community/langchain_community/document_loaders/recursive_url_loader.py#L51-L51

Resolved in https://github.com/langchain-ai/langchain/pull/15559

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/langchain
Introduced in: 0Fixed in: 0.1.0
Fixpip install --upgrade 'langchain>=0.1.0'

References