CVE-2026-3276
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.
Scoring
- Severity
- MEDIUM
- CVSS base score
- 6.3
- CVSS vector
- 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
- EPSS probability
- 0.49%
- CWE
- CWE-407
- Published
- 2026-06-03
- Last modified
- 2026-08-13
Affected products
- Python Software Foundation CPython
- Python Software Foundation CPython
- Python Software Foundation CPython
- Python Software Foundation CPython
- Python Software Foundation CPython
- Python Software Foundation CPython
Weakness type
Related vulnerabilities
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- CVE-2023-54395 — PocketMine-MP before 4.12.5 Denial of Service via ModalFormResponsePacket
- CVE-2026-86435 — commonmark 1.5.0 before 2.8.4 Denial of Service via Footnote
- CVE-2026-86434 — commonmark 2.0.0 through 2.8.3 Denial of Service via Slug Collision
- CVE-2026-86433 — commonmark 1.5.0 before 2.8.4 Denial of Service via Attributes
- CVE-2026-86430 — league/commonmark before 2.9.1 Denial of Service via parsing
- CVE-2026-86429 — commonmark before 2.9.1 Denial of Service via SmartPunct and Attributes