Net-IDN-UTS46 up to 2.589 Punycode Encoding to_ascii resource consumption

Summaryinfo

A vulnerability was found in Net-IDN-UTS46 up to 2.589. It has been rated as problematic. The affected element is the function to_ascii of the component Punycode Encoding. The manipulation leads to resource consumption. This vulnerability is traded as CVE-2026-87081. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Net-IDN-UTS46 up to 2.589. This issue affects the function to_ascii of the component Punycode Encoding. The manipulation with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. The summary by CVE is:

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.

It is possible to read the advisory at metacpan.org. The identification of this vulnerability is CVE-2026-87081 since 09/08/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 2.590 eliminates this vulnerability.

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Productinfo

Name

• Net-IDN-UTS46

Version

• 2.589

CPE 2.3info

• 🔒

CPE 2.2info

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