# CVE-2026-3276

## Summary

- **CVE ID:** CVE-2026-3276
- **Severity:** MEDIUM
- **CVSS Score:** 6.3 (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N)
- **CWE:** CWE-407
- **Published:** Jun 3, 2026
- **Last Modified:** Aug 13, 2026

## 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.

## Affected Products

- Python Software Foundation — CPython (0)
- Python Software Foundation — CPython (3.14.0)
- Python Software Foundation — CPython (3.15.0a1)
- Python Software Foundation — CPython (3.11.0)
- Python Software Foundation — CPython (3.12.0)
- Python Software Foundation — CPython (3.13.0)

## References

- [CNA](https://mail.python.org/archives/list/security-announce@python.org/thread/PP5HB4K7727OBBM76KA2ILID76K3OZGZ/)
- [CNA](https://github.com/python/cpython/pull/149080)
- [CNA](https://github.com/python/cpython/issues/149079)
- [CVE](http://www.openwall.com/lists/oss-security/2026/06/03/15)
- [CNA](https://github.com/python/cpython/commit/6b505d1f41f8f3ea0fe5a4786d3a8fff1875cfc0)
- [CNA](https://github.com/python/cpython/commit/991224b1e8311c85f198f6dd8208bf8cff7fc26f)
- [CNA](https://github.com/python/cpython/commit/ba785b88add96acbf403d65cb157fb2743a33a32)
- [CNA](https://github.com/python/cpython/commit/c5512bd7c1dc28055660565275012766941d3066)
- [CNA](https://github.com/python/cpython/commit/90748760d38ca3ac5fc6788a69becab905c95598)
- [CNA](https://github.com/python/cpython/commit/d3ab945af25b28dfe13ac6cb40c124a01b33ce1f)
- [CNA](https://github.com/python/cpython/commit/db744c0776c1d5dd11aaa70eff2a6993c408bacc)
- [CNA](https://github.com/python/cpython/commit/e322a1857084d521f79f45181b776f62e6acfc2c)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.49%
- **EPSS Percentile:** 40.3

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._