CVE & CISA-KEV Catalog

CVE-2026-3276

MEDIUM
6.3
CVSS v4
NVD

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.

How to fix

Remediation Available
libpython3.10Ubuntu
Fixed in:3.10.12-1~22.04.16USN-8509-1
libpython3.12t64Ubuntu
Fixed in:3.12.3-1ubuntu0.15USN-8509-1
python3.10Ubuntu
Fixed in:3.10.12-1~22.04.16USN-8509-1
python3.12Ubuntu
Fixed in:3.12.3-1ubuntu0.15USN-8509-1

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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v4 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone

Impact

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

Exploit Intelligence

0.49%probability of exploitation in 30 days
40thpercentile

Low risk: more likely to be exploited than 40% of all known CVEs.

References

Related Vulnerabilities

Other CWE-407 vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2020-27223Medium5.278%-Fix
CVE-2022-36021Medium5.560%-Fix
CVE-2021-33582High7.53.1%-Fix
CVE-2024-43485High7.53.1%-Fix
CVE-2024-43484High7.52.9%-Fix
CVE-2016-10396High7.52.9%--

Common questions

How do I fix CVE-2026-3276?

Published advisories record a fix for 4 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2026-3276 being actively exploited?

Not that we know of. CVE-2026-3276 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.49% is the estimated probability that it will be exploited in the next 30 days. That is higher than 40% of all scored CVEs.

How severe is CVE-2026-3276?

CVE-2026-3276 has a CVSS v4 base score of 6.3, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-3276 affect?

Published advisories record a fix for libpython3.10 (Ubuntu), libpython3.12t64 (Ubuntu), python3.10 (Ubuntu), python3.12 (Ubuntu). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-13.