Description
Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode.

The XS backend allocates the scalar it returns before it validates the input, sizing the buffer at twice the input length. The scalar is released only on the success path, so each of the three croaks that reject a label leaves the scalar and its buffer allocated. Nothing bounds the label length in the to-Unicode direction, since the 63-byte DNS limit is checked only when converting to ASCII.

Only the XS backend is affected.

A sender who supplies invalid labels grows the process by twice the label length per rejected call, with no successful call needed.
Published: 2026-09-22
Score: 9.1 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Solution

Upgrade to Net-IDN-Encode 2.590-TRIAL or later.

Tracking

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Advisories

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History

Tue, 22 Sep 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 22 Sep 2026 07:30:00 +0000

Type Values Removed Values Added
Description Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode. The XS backend allocates the scalar it returns before it validates the input, sizing the buffer at twice the input length. The scalar is released only on the success path, so each of the three croaks that reject a label leaves the scalar and its buffer allocated. Nothing bounds the label length in the to-Unicode direction, since the 63-byte DNS limit is checked only when converting to ASCII. Only the XS backend is affected. A sender who supplies invalid labels grows the process by twice the label length per rejected call, with no successful call needed.
Title Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode
Weaknesses CWE-401
References

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: CPANSec

Published:

Updated: 2026-09-22T12:33:22.356Z

Reserved: 2026-09-08T19:22:20.005Z

Link: CVE-2026-87078

cve-icon Vulnrichment

Updated: 2026-09-22T12:33:04.415Z

cve-icon NVD

Status : Received

Published: 2026-09-22T08:16:40.530

Modified: 2026-09-22T13:17:11.307

Link: CVE-2026-87078

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-22T08:30:17Z

Weaknesses
  • CWE-401

    Missing Release of Memory after Effective Lifetime