CVE-2026-97688

NameCVE-2026-97688
Descriptionurllib3 is an HTTP client library for Python. From 2.6.2 until 2.8.0, HTTPResponse.stream and HTTPResponse.read_chunked can enter an infinite loop because the Deflate decoder retains trailing bytes as unconsumed input after reaching end-of-stream and repeatedly decodes them without progress. The issue occurs when an untrusted server sends a chunked Deflate response whose decoded body exceeds a positive finite chunk size and whose encoded body has trailing bytes, specifically a response with Transfer-Encoding: chunked and Content-Encoding: deflate, content decoding enabled, and the positive finite amt=N streaming chunk size. The attack mechanism is that a malicious server returns a compressed chunked response with trailing bytes after the Deflate stream. The impact is excessive CPU usage and a request that does not complete, and network read timeouts do not interrupt the loop because no further socket read occurs. This issue is fixed in version 2.8.0.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
python-urllib3 (PTS)bookworm, bookworm (security)1.26.12-1+deb12u4fixed
trixie (security), trixie2.3.0-3+deb13u2fixed
forky, sid2.8.0-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
python-urllib3sourcebookworm(not affected)
python-urllib3sourcetrixie(not affected)
python-urllib3source(unstable)2.8.0-1

Notes

[trixie] - python-urllib3 <not-affected> (Vulnerable code not present, introduced in 2.6.2)
[bookworm] - python-urllib3 <not-affected> (Vulnerable code not present, introduced in 2.6.2)
https://github.com/urllib3/urllib3/security/advisories/GHSA-gh4c-6fx4-qh6g
Fixed by: https://github.com/urllib3/urllib3/commit/ea2ad7b21a80da3632f80016526a18864586077f (2.8.0)

Search for package or bug name: Reporting problems