GHSA-gh4c-6fx4-qh6g: urllib3 (CVE-2026-97688)

Package	Ecosystem	Affected	Fixed in
urllib3	PyPI	>=2.6.2, <2.8.0	2.8.0

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

urllib3 versions 2.6.2 through 2.7.0 are vulnerable when a chunked response with Content-Encoding deflate contains bytes after the end of the Deflate stream and is streamed with a finite chunk size. A malicious server can make the client loop indefinitely while decoding, consuming CPU and preventing the request from completing; network read timeouts do not interrupt it. Upgrade to urllib3 2.8.0. If upgrading is not immediately possible, set decode_content=False for untrusted responses or reject streamed Deflate-encoded responses.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
6.9	Medium	4.0	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0029, the 21st percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

15 Sept 2026, 19:42 UTC Published by the maintainers as a GitHub repository advisory
31 Oct 2026, 14:09 UTC First seen by agentprime
31 Oct 2026, 14:09 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.