CVE-2026-87079Hinoki check available

CPU exhaustion via quadratic Punycode decoding

Published Sep 22, 2026 · Updated Sep 22, 2026

Algorithmic complexity in Net-IDN-Encode before 2.590 allows attackers to exhaust CPU by decoding an oversized Punycode label. The XS backend repeatedly scans and inserts into its growing UTF-8 buffer, while the pure-Perl backend repeatedly scans a UTF-8-flagged copy. A consuming application must pass an unbounded label to decode_punycode, domain_to_unicode, or uts46_to_unicode, causing a hang under sustained processing.

CVSS severityUnavailable
Unscored
EPSS probability0.38%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Algorithmic complexity in Net-IDN-Encode before 2.590 allows attackers to exhaust CPU by decoding an oversized Punycode label. The XS backend repeatedly scans and inserts into its growing UTF-8 buffer, while the pure-Perl backend repeatedly scans a UTF-8-flagged copy. A consuming application must pass an unbounded label to decode_punycode, domain_to_unicode, or uts46_to_unicode, causing a hang under sustained processing.

The record

CVE
CVE-2026-87079
Published
Sep 22, 2026
Updated
Sep 22, 2026
Vendor
Paul Johnson
Product
Net-IDN-Encode
Classifications
T1499
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 22, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2.590

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Paul Johnson · Net-IDN-Encodeversion=0 <2.590

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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