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 :
Dec. 1, 2025, 6:16 p.m.
Last Modified :
Dec. 30, 2025, 3:08 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | MEDIUM | 28c92f92-d60d-412d-b760-e73465c3df22 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Limit the maximum response size on clients.
- Prefer chunked transfer encoding over Content-Length.
- Implement robust error handling for oversized responses.
Public PoC/Exploit Available at Github
CVE-2025-13836 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-13836.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-13836 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-13836
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-13836 vulnerability anywhere in the article.
-
The Hacker News
⚡ Weekly Recap: MongoDB Attacks, Wallet Breaches, Android Spyware, Insider Crime & More
Dec 29, 2026Ravie LakshmananHacking News / Cybersecurity Last week's cyber news in 2025 was not about one big incident. It was about many small cracks opening at the same time. Tools people trust ev ... Read more
The following table lists the changes that have been made to the
CVE-2025-13836 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Dec. 30, 2025
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H Added CWE CWE-125 Added CPE Configuration OR *cpe:2.3:a:python:python:*:*:*:*:*:*:*:* versions up to (excluding) 3.13.11 *cpe:2.3:a:python:python:3.15.0:alpha1:*:*:*:*:*:* *cpe:2.3:a:python:python:3.15.0:alpha2:*:*:*:*:*:* *cpe:2.3:a:python:python:3.14.0:-:*:*:*:*:*:* Added Reference Type Python Software Foundation: https://github.com/python/cpython/commit/14b1fdb0a94b96f86fc7b86671ea9582b8676628 Types: Patch Added Reference Type Python Software Foundation: https://github.com/python/cpython/commit/289f29b0fe38baf2d7cb5854f4bb573cc34a6a15 Types: Patch Added Reference Type Python Software Foundation: https://github.com/python/cpython/commit/4ce27904b597c77d74dd93f2c912676021a99155 Types: Patch Added Reference Type Python Software Foundation: https://github.com/python/cpython/commit/5a4c4a033a4a54481be6870aa1896fad732555b5 Types: Patch Added Reference Type Python Software Foundation: https://github.com/python/cpython/issues/119451 Types: Issue Tracking, Patch Added Reference Type Python Software Foundation: https://github.com/python/cpython/pull/119454 Types: Issue Tracking, Patch Added Reference Type Python Software Foundation: https://mail.python.org/archives/list/[email protected]/thread/OQ6G7MKRQIS3OAREC3HNG3D2DPOU34XO/ Types: Vendor Advisory -
CVE Modified by [email protected]
Dec. 22, 2025
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/14b1fdb0a94b96f86fc7b86671ea9582b8676628 -
CVE Modified by [email protected]
Dec. 05, 2025
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/289f29b0fe38baf2d7cb5854f4bb573cc34a6a15 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Dec. 02, 2025
Action Type Old Value New Value Added CWE CWE-400 -
CVE Modified by [email protected]
Dec. 02, 2025
Action Type Old Value New Value Added Reference https://mail.python.org/archives/list/[email protected]/thread/OQ6G7MKRQIS3OAREC3HNG3D2DPOU34XO/ -
CVE Modified by [email protected]
Dec. 01, 2025
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/4ce27904b597c77d74dd93f2c912676021a99155 Added Reference https://github.com/python/cpython/commit/5a4c4a033a4a54481be6870aa1896fad732555b5 -
New CVE Received by [email protected]
Dec. 01, 2025
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added Reference https://github.com/python/cpython/issues/119451 Added Reference https://github.com/python/cpython/pull/119454