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CVE-2026-45409
Published:May 19, 2026
Updated:May 20, 2026
This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. Payloads such as ""\u0660" * N" or ""\u30fb" * N + "\u6f22"" utilize the "valid_contexto" function prior to length rejection, and for high values of "N" will take a long time to process. Impact A specially crafted argument to the "idna.encode()" function could consume significant resources. This may lead to a denial-of-service. Patches Starting in version 3.14, the function rejects long inputs as soon as practicable prior to any further processing to minimize resource consumption. In version 3.15, this approach was extended to lesser used alternate functions (i.e. per-label conversions and codec support). Workarounds Domain names cannot exceed 253 characters in length, if this length limit is enforced prior to passing the domain to the "idna.encode()" function it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application.
Affected Packages
idna (CONDA):
Affected version(s) >=2.0 <3.15
Fix Suggestion:
Update to version 3.15
idna (PYTHON):
Affected version(s) >=0.1 <3.15
Fix Suggestion:
Update to version 3.15
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CVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Inefficient Regular Expression Complexity