01 Record

CVE-2026-45409

Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix

MediumPUBLISHEDCNA: GitHub_M

CNA base score6.9 CVSS v4.0CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

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02 Description

Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix

03 Exploitation and scoring

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.40% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 34.7% of scored records. A rank, not a probability.

NVD base score

6.9 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/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

NVD analysis status

Analyzed. NVD last modified this record on 2026-07-23.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2026-06-05 22:06Z4 MO AGO

Last updated

2026-06-08 16:34Z4 MO AGO

Reserved

2026-05-12

Assigning CNA

GitHub_M

Record state

PUBLISHED

Severity

Medium (CVSS 6.9)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Weaknesses

CWE-1333Inefficient Regular Expression ComplexityBase
CWE-770Allocation of Resources Without Limits or ThrottlingBase

Data version

5.2

Document digest

6ac4ad90391f427ae2db35519860d5ed7740fef5ad744b16c464bf6a39a4ef75

05 Affected products

VendorProductVersionsPlatforms

kjdidna< 3.15—

06 References

github.comhttps://github.com/kjd/idna/security/advisories/GHSA-65pc-fj4g-8rjxx_refsource_CONFIRM

07 Fixed in

AlmaLinux 8

python3-idna
Fixed in 2.5-8.el8_10

AlmaLinux 9

python3-idna
Fixed in 2.10-8.el9_8

AlmaLinux 10

python3-idna
Fixed in 3.7-6.el10_2

CloudLinux 8

python3-idna
Fixed in 2.5-8.el8_10

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

CloudLinux 9

python3-idna
Fixed in 2.10-8.el9_8

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

CloudLinux 10

python3-idna
Fixed in 3.7-6.el10_2

Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.

Debian 12

python-idna
No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

python-idna
Fixed in 3.10-1+deb13u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

python-idna
Fixed in 3.11-1.1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.