CVE-2026-3276
Potential DoS via quadratic complexity in unicodedata.normalize()
Description
unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating Canonical Combining Class values. This affects all normalization forms.
INFO
Published Date :
June 3, 2026, 4:16 p.m.
Last Modified :
June 16, 2026, 3:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-3276
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | 28c92f92-d60d-412d-b760-e73465c3df22 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Validate and sanitize Unicode input before normalization.
- Limit processing time for normalization operations.
- Update to a version with improved Unicode handling.
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-2026-3276.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-3276 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-2026-3276
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).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-3276 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-3276 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.
-
CVE Modified by [email protected]
Jun. 16, 2026
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/90748760d38ca3ac5fc6788a69becab905c95598 -
CVE Modified by [email protected]
Jun. 04, 2026
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/6b505d1f41f8f3ea0fe5a4786d3a8fff1875cfc0 Added Reference https://github.com/python/cpython/commit/991224b1e8311c85f198f6dd8208bf8cff7fc26f Added Reference https://github.com/python/cpython/commit/ba785b88add96acbf403d65cb157fb2743a33a32 Added Reference https://github.com/python/cpython/commit/c5512bd7c1dc28055660565275012766941d3066 -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jun. 03, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/06/03/15 -
New CVE Received by [email protected]
Jun. 03, 2026
Action Type Old Value New Value Added Description unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating Canonical Combining Class values. This affects all normalization forms. 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: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-407 Added Reference https://github.com/python/cpython/issues/149079 Added Reference https://github.com/python/cpython/pull/149080 Added Reference https://mail.python.org/archives/list/[email protected]/thread/PP5HB4K7727OBBM76KA2ILID76K3OZGZ/