Skip to main content
CVE-2026-3276VulnerabilityPublished Updated

unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long

Source GCVE Database

0
Compare
Authoritative record:CVE-2026-3276· Medium 6.3

Not known to be exploited · CVSS 6.3 Medium · fixed in 3.15.0b2 : update CPython when convenient.

Data as of 10 Nov 2026, 16:36 UTC

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (PSF)CVSS 4.06.3
Patch
Available – fixed in 3.15.0b2, 3.14.6, 3.13.14 +4
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Python Software FoundationCPythonAffected
  • >=3.15.0a1 <3.15.0b2
Fixed in
  • 3.15.0b2
Python Software FoundationCPythonAffected
  • >=3.14.0 <3.14.6
Fixed in
  • 3.14.6
Python Software FoundationCPythonAffected
  • >=3.13.0 <3.13.14
Fixed in
  • 3.13.14
Python Software FoundationCPythonAffected
  • >=3.12.0 <3.12.14
Fixed in
  • 3.12.14
Python Software FoundationCPythonAffected
  • >=3.11.0 <3.11.16
Fixed in
  • 3.11.16
Python Software FoundationCPythonAffected
  • <3.10.21
Fixed in
  • 3.10.21

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

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.

References

Community reviews

Loading reviews…