---
title: "CVE-2026-74766: Net::IDN::Punycode - Use After Free"
description: "Net::IDN::Punycode 2.301 before 2.590 for Perl contains a use-after-free caused by improper buffer reallocation in decode_punycode, letting attackers read and write freed heap memory during punycode decoding, exploit requires attacker-supplied input."
url: https://panop.io/threat-heartbeat/CVE-2026-74766/
---

# CVE-2026-74766 Net::IDN::Punycode - Use After Free

Net::IDN::Punycode 2.301 before 2.590 for Perl contains a use-after-free caused by improper buffer reallocation in decode\_punycode, letting attackers read and write freed heap memory during punycode decoding, exploit requires attacker-supplied input.

CVSS base score 8.4 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.14% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-74766)

## Details

Type

Use After Free

Impact

Remote Code Execution, Denial Of Service

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Published

22 September 2026

Updated

15 October 2026

Weakness

[CWE-416](https://cwe.mitre.org/data/definitions/416.html)

## Vendor fix

Upgrade to version 2.590 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-74766](https://nvd.nist.gov/vuln/detail/CVE-2026-74766)
- [https://www.cve.org/CVERecord?id=CVE-2016-15059](https://www.cve.org/CVERecord?id=CVE-2016-15059)
- [https://github.com/robrwo/Net-IDN-Encode/commit/259e74c5739175b063c5393a4ce4a0705678ba61.patch](https://github.com/robrwo/Net-IDN-Encode/commit/259e74c5739175b063c5393a4ce4a0705678ba61.patch)
- [https://github.com/robrwo/Net-IDN-Encode/commit/2fbc71e4d8517ab65c5d5d35fda086371b735a3f.patch](https://github.com/robrwo/Net-IDN-Encode/commit/2fbc71e4d8517ab65c5d5d35fda086371b735a3f.patch)
- [https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes](https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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