CVE-2026-74766

Heap memory corruption via stale insertion pointer

Published Sep 22, 2026 · Updated Sep 22, 2026

Heap use-after-free in Net::IDN::Punycode 2.301 through 2.589 allows attackers to corrupt memory via a crafted Punycode label. decode_punycode calculates an insertion pointer before enlarging its scalar output buffer, then retains that stale pointer after reallocation and uses it to move data and write the decoded code point. Only programs using the XS backend to decode attacker-supplied labels expose the freed-memory read and write.

CVSS severityUnavailable
Unscored
EPSS probability0.14%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap use-after-free in Net::IDN::Punycode 2.301 through 2.589 allows attackers to corrupt memory via a crafted Punycode label. decode_punycode calculates an insertion pointer before enlarging its scalar output buffer, then retains that stale pointer after reallocation and uses it to move data and write the decoded code point. Only programs using the XS backend to decode attacker-supplied labels expose the freed-memory read and write.

The record

CVE
CVE-2026-74766
Published
Sep 22, 2026
Updated
Sep 22, 2026
Vendor
Paul Johnson
Product
Net::IDN::Punycode
Classifications
Unavailable
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=2.301 <2.590

What conditions does exploitation require?

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

What is affected?

Paul Johnson · Net::IDN::Punycodeversion=2.301 <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

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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