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CVE-2026-3276Potential DoS via quadratic complexity in unicodedata.normalize()
- 6.3MediumCVSS base score
- 0.51%Exploitation in 30 daysEPSS · top 56% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By PSF
- 3 months later
· 3 months later
Published
- 5 months later
· 5 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| PSFCNA (assigner) | 4.0 | Medium6.3 | 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 |
| NVDNVD · Awaiting Analysis | 4.0 | Medium6.3 | 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/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 |
- EPSS (exploitation in 30 days)
- 0.51% · top 56% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.3.
Affected products
Python Software Foundation · CPython
- affected < 3.10.21
- affected 3.11.0 – < 3.11.16
- affected 3.12.0 – < 3.12.14
- affected 3.13.0 – < 3.13.14
- affected 3.14.0 – < 3.14.6
- affected 3.15.0a1 – < 3.15.0b2
References
References13
- https://mail.python.org/archives/list/[email protected]/thread/PP5HB4K7727OBBM76KA2ILID76K3OZGZ/ (opens in a new tab)vendor-advisory
- https://github.com/python/cpython/pull/149080 (opens in a new tab)patch
- https://github.com/python/cpython/issues/149079 (opens in a new tab)issue-tracking
- https://github.com/python/cpython/commit/6b505d1f41f8f3ea0fe5a4786d3a8fff1875cfc0 (opens in a new tab)patch
- https://github.com/python/cpython/commit/991224b1e8311c85f198f6dd8208bf8cff7fc26f (opens in a new tab)patch
- https://github.com/python/cpython/commit/ba785b88add96acbf403d65cb157fb2743a33a32 (opens in a new tab)patch
- https://github.com/python/cpython/commit/c5512bd7c1dc28055660565275012766941d3066 (opens in a new tab)patch
- https://github.com/python/cpython/commit/90748760d38ca3ac5fc6788a69becab905c95598 (opens in a new tab)patch
- https://github.com/python/cpython/commit/d3ab945af25b28dfe13ac6cb40c124a01b33ce1f (opens in a new tab)patch
- https://github.com/python/cpython/commit/db744c0776c1d5dd11aaa70eff2a6993c408bacc (opens in a new tab)patch
- https://github.com/python/cpython/commit/e322a1857084d521f79f45181b776f62e6acfc2c (opens in a new tab)patch
- http://www.openwall.com/lists/oss-security/2026/06/03/15 (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-34103 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-3276)Record last updated .