Denial of service via late length rejection
Published Jun 5, 2026 · Updated Jun 5, 2026
Resource-exhaustion denial of service in Kim Davies idna before 3.15 allows remote attackers to interrupt services via crafted domains. The valid_contexto path processes arbitrarily long CONTEXTO-label input before enforcing the domain-length limit, causing processing time to grow with attacker-controlled input. Exploitation requires a higher-level application to pass unvalidated, attacker-controlled domain data into an affected conversion path, where CPU consumption can delay or interrupt that application.
Summary
What happened
Resource-exhaustion denial of service in Kim Davies idna before 3.15 allows remote attackers to interrupt services via crafted domains. The valid_contexto path processes arbitrarily long CONTEXTO-label input before enforcing the domain-length limit, causing processing time to grow with attacker-controlled input. Exploitation requires a higher-level application to pass unvalidated, attacker-controlled domain data into an affected conversion path, where CPU consumption can delay or interrupt that application.
The record
- CVE
- CVE-2026-45409
- Published
- Jun 5, 2026
- Updated
- Jun 5, 2026
- Vendor
- Kim Davies
- Product
- idna
- Classifications
- CWE-1333, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 5, 2026CVE publishedPublication date reported by the CVE source.
- Jun 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 3.15
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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