CVE-2026-31958
Tornado has a DoS due to too many multipart parts
Description
Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.
INFO
Published Date :
March 11, 2026, 8:16 p.m.
Last Modified :
April 1, 2026, 3:23 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Tornado to version 6.5.5 or later.
- Configure max_body_size appropriately.
- Monitor resource usage for large uploads.
Public PoC/Exploit Available at Github
CVE-2026-31958 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-2026-31958.
| URL | Resource |
|---|---|
| https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc | Vendor Advisory |
| https://lists.debian.org/debian-lts-announce/2026/04/msg00000.html |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-31958 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-2026-31958
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).
DSA and DLA for Debian last 14 days
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-31958 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-31958 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.
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CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Apr. 01, 2026
Action Type Old Value New Value Added Reference https://lists.debian.org/debian-lts-announce/2026/04/msg00000.html -
Initial Analysis by [email protected]
Mar. 16, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:tornadoweb:tornado:*:*:*:*:*:*:*:* versions up to (excluding) 6.5.5 Added Reference Type GitHub, Inc.: https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc Types: Vendor Advisory -
New CVE Received by [email protected]
Mar. 11, 2026
Action Type Old Value New Value Added Description Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/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 CWE CWE-400 Added Reference https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc