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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-87078
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-22 08:16:40 UTC
Updated2026-09-22 19:07:00 UTC
DescriptionNet::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.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from ADP

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

EPSS: 0.003640000 probability, percentile 0.302120000 (date 2026-09-23)

Problem Types: CWE-401 | CWE-401 CWE-401 Missing Release of Memory after Effective Lifetime

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

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

References

ReferenceSourceLinkTags
www.openwall.com/lists/oss-security/2026/09/22/13 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
github.com/robrwo/Net-IDN-Encode/commit/92572f726e48af5559de4cc8a831463b... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
github.com/robrwo/Net-IDN-Encode/commit/edad63e0eeeeb18d93bc6dfe4d9dcdff... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2016-12-07T00:00:00.000ZVersion 2.302 released, introducing the defect.
CNA2026-09-17T00:00:00.000ZVersion 2.590-TRIAL released with fix.

Solutions

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

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