Vulnerability · Published Sep 29, 2026 · Assigned by GitHub_M
CVE-2026-97689urllib3: HTTPResponse.stream()/read_chunked() buffers an unbounded chunk-size line into memory
High 8.9
In plain English
A high-severity resource allocation without limits in urllib3 from urllib3. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
urllib3 is an HTTP client library for Python. From 1.10.3 until 2.8.0, the HTTPResponse.read_chunked and HTTPResponse.stream methods can allocate unbounded memory because the streaming chunk parser buffers the chunk-size field until newline or EOF without a length bound. The trigger is that a malicious server returns Transfer-Encoding: chunked followed by a very long run of bytes without a newline. The attack mechanism is that a malicious HTTP server sends a very long unterminated chunk-size line. The impact is that unbounded memory allocation can exhaust the client process. This issue is fixed in version 2.8.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | python3-urllib3 | 1.26.19-4.el10_2.2 | ALSA-2026:85930 |
| AlmaLinux:8 | python3-urllib3 | 1.24.2-11.el8_10 | ALSA-2026:90759 |
| AlmaLinux:9 | python3-urllib3 | 1.26.5-8.el9_8.2 | ALSA-2026:90494 |
| AlmaLinux:8 | python3.12-urllib3 | 1.26.19-5.el8_10 | ALSA-2026:92474 |
| AlmaLinux:9 | python3.12-urllib3 | 1.26.19-3.el9_8.2 | ALSA-2026:85929 |
| AlmaLinux:10 | python3.14-urllib3 | 2.6.3-2.el10_2.6 | ALSA-2026:84578 |
| AlmaLinux:9 | python3.14-urllib3 | 2.6.3-2.el9_8.6 | ALSA-2026:84577 |
| Debian:12 | python-urllib3 | no fix listed | DEBIAN-CVE-2026-97689 |
| Debian:13 | python-urllib3 | no fix listed | DEBIAN-CVE-2026-97689 |
| Debian:14 | python-urllib3 | 2.8.0-1 | DEBIAN-CVE-2026-97689 |
| PyPI | urllib3 | 2.8.0 | GHSA-vxq7-64xx-v4gw |
| PyPI | urllib3 | 2.8.0 | PYSEC-2026-4177 |
| Rocky Linux:10 | python-urllib3 | 0:1.26.19-4.el10_2.2 | RLSA-2026:85930 |
| Rocky Linux:8 | python-urllib3 | 0:1.24.2-11.el8_10 | RLSA-2026:90759 |
| Rocky Linux:9 | python-urllib3 | 0:1.26.5-8.el9_8.2 | RLSA-2026:90494 |
| Rocky Linux:8 | python3.12-urllib3 | 0:1.26.19-5.el8_10 | RLSA-2026:92474 |
| Rocky Linux:9 | python3.12-urllib3 | 0:1.26.19-3.el9_8.2 | RLSA-2026:85929 |
| Rocky Linux:10 | python3.14-urllib3 | 0:2.6.3-2.el10_2.6 | RLSA-2026:84578 |
| Rocky Linux:9 | python3.14-urllib3 | 0:2.6.3-2.el9_8.6 | RLSA-2026:84577 |
| Ubuntu:26.10 | python-pip | no fix listed | UBUNTU-CVE-2026-97689 |
| Ubuntu:22.04:LTS | python-urllib3 | 1.26.5-1~exp1ubuntu0.8 | UBUNTU-CVE-2026-97689 |
| Ubuntu:22.04:LTS | python-urllib3 | 1.26.5-1~exp1ubuntu0.8 | USN-8926-1 |
| Ubuntu:24.04:LTS | python-urllib3 | 2.0.7-1ubuntu0.8 | UBUNTU-CVE-2026-97689 |
| Ubuntu:24.04:LTS | python-urllib3 | 2.0.7-1ubuntu0.8 | USN-8926-1 |
| Ubuntu:26.04:LTS | python-urllib3 | 2.6.3-1ubuntu1.2 | UBUNTU-CVE-2026-97689 |
| Ubuntu:26.04:LTS | python-urllib3 | 2.6.3-1ubuntu1.2 | USN-8926-1 |
Affected products (as reported)
Weakness: CWE-770 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
References
- https://github.com/urllib3/urllib3/security/advisories/GHSA-vxq7-64xx-v4gw x_refsource_CONFIRM
- https://github.com/urllib3/urllib3/commit/cd770b059b543be29298ea5c52afb0b1b090f5ed x_refsource_MISC
- https://github.com/urllib3/urllib3/releases/tag/2.8.0 x_refsource_MISC