CVE-2026-87081 Details
Description
Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii. to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.
A vulnerability in Net::IDN::UTS46 for Perl, affecting versions prior to 2.590, allows for CPU exhaustion through quadratic punycode encoding of overlong labels. The issue arises because the 'to_ascii' function encodes each label before applying the 63-byte DNS length limit. This implementation, which follows RFC 3492, creates a scenario where labels with distinct non-ASCII characters can cause a quadratic increase in processing time. The vulnerability is present in all ASCII conversion functions within the distribution, including 'domain_to_ascii' and 'email_to_ascii', which rely on 'to_ascii'.
Users are advised to upgrade to Net-IDN-Encode version 2.590-TRIAL or later.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 22, 2026CISA-ADP
Assessed Sep 22, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/robrwo/Net-IDN-Encode/commit/5ac3315131264670efcd3a29857b651506dfee8e.patch | CPANSec | Source CodeVendor |
| https://github.com/robrwo/Net-IDN-Encode/commit/ea34f812d7dc67f3b211f4d92e74c6a7e24d764a.patch | CPANSec | Source CodeVendor |
| https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes | CPANSec | Source CodeVendor |
| http://www.openwall.com/lists/oss-security/2026/09/22/16 | CVE | AdvisoryMailing ListRemedy |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-407 | Inefficient Algorithmic Complexity | CPANSec |
Affected Products
| Product | Versions |
|---|---|
| Net::IDN::UTS46 | < 2.590 |
CPE
Remediation
| |
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 22, 2026 | CVE Modified | CVE |
| Sep 22, 2026 | CVE Modified | CISA-ADP |
| Sep 22, 2026 | New CVE Received | CPANSec |