The vulnerability resides in the HTMLHeaderTextSplitter.split_text_from_url method, which validates the original URL but then follows HTTP redirects without revalidation. An attacker who can supply a URL can direct the library to redirect to an internal or localhost address. If the application returns the resulting Document object to the requester, sensitive data from internal services could be exfiltrated. If the application simply stores or processes the Document internally without exposing its contents, the risk is limited to a typical SSRF scenario. The weakness is a Server‑Side Request Forgery flaw identified as CWE‑918.

This issue affects installations of langchain-text-splitters older than version 1.1.2 on any platform where the application can invoke split_text_from_url. The fix is included in release 1.1.2. Users of langchain-text-splitters before that version are vulnerable.

The CVSS score of 6.5 indicates a moderate severity. The EPSS score of less than 1 % suggests a very low probability of exploitation at this time. The vulnerability is not listed in CISA’s KEV catalog. Exploitation requires the attacker to provide a URL to the vulnerable function, which then performs a redirection to an internal service. The undefined nature of the application’s handling of returned Documents affects the overall impact; if the contents are exposed to the user, the damage could be significant, otherwise only SSRF occurs.