Is CVE-2026-9375 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-9375 being exploited in the wild.

How severe is CVE-2026-9375?

High severity, with a CVSS score of 7.5, published 19 June 2026.

Is there a fix for CVE-2026-9375?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-9375 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-9375?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-9375: urllib3 denial of service via Brotli decompression bomb bypass

CVE-2026-9375 · Severity: high · CVSS 7.5 · Published 2026-06-19

A vulnerability in the popular urllib3 Python library could allow a malicious website to crash an application. By sending a specially crafted compressed response, an attacker can force the application to consume all available memory, leading to a denial of service. This affects systems that use urllib3 or the requests library to stream data from untrusted internet sources.

Quick answers

Is CVE-2026-9375 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-9375 being exploited in the wild.
How severe is CVE-2026-9375?: High severity, with a CVSS score of 7.5, published 19 June 2026.
Which products and versions are affected?: urllib3 urllib3 2.6.3.
Is there a fix for CVE-2026-9375?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-9375 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-9375?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

urllib3 2.6.3 is vulnerable to an uncontrolled resource consumption (CWE-400) issue when processing Brotli-compressed streams with `preload_content=False`. The vulnerability stems from three flaws in `response.py` that bypass the `max_length` safety limits introduced in version 2.6.0: buffer arithmetic errors producing negative `max_length` values, `flush_decoder` overriding limits to `-1`, and `_flush_decoder()` defaulting to unlimited decompression. A remote attacker controlling an HTTP server can exploit this to trigger an out-of-memory (OOM) condition. The issue is addressed in version 2.7.0.

Affected products

urllib3 urllib3 2.6.3

Timeline

2026-06-19: disclosed
2026-06-19: advisory

References

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