CVE-2025-13836

Excessive read buffering DoS in http.client

Description

When reading an HTTP response from a server, if no read amount is specified, the default behavior will be to use Content-Length. This allows a malicious server to cause the client to read large amounts of data into memory, potentially causing OOM or other DoS.

INFO

Published Date :

2025-12-01T18:02:38.483Z

Last Modified :

2026-03-03T14:41:48.702Z

Source :

PSF

AFFECTED PRODUCTS

The following products are affected by CVE-2025-13836 vulnerability.

Vendors	Products
Python	Cpython Python

REFERENCES

Here, you will find a curated list of external links that provide in-depth information to CVE-2025-13836.

URL	Resource
https://github.com/python/cpython/commit/14b1fdb0a94b96f86fc7b86671ea9582b8676628
https://github.com/python/cpython/commit/289f29b0fe38baf2d7cb5854f4bb573cc34a6a15
https://github.com/python/cpython/commit/4ce27904b597c77d74dd93f2c912676021a99155
https://github.com/python/cpython/commit/5a4c4a033a4a54481be6870aa1896fad732555b5
https://github.com/python/cpython/commit/5dc101675fd22918facbbe0fecdc821502beaaf0
https://github.com/python/cpython/commit/afc40bdd3dd71f343fd9016f6d8eebbacbd6587c
https://github.com/python/cpython/issues/119451
https://github.com/python/cpython/pull/119454
https://mail.python.org/archives/list/[email protected]/thread/OQ6G7MKRQIS3OAREC3HNG3D2DPOU34XO/
https://nvd.nist.gov/vuln/detail/CVE-2025-13836
https://www.cve.org/CVERecord?id=CVE-2025-13836