Net::IDN::Punycode up to 2.589 XS backend encode_punycode integer overflow

Summaryinfo

A vulnerability was found in Net::IDN::Punycode up to 2.589. It has been declared as critical. Impacted is the function encode_punycode of the component XS backend. Executing a manipulation can lead to integer overflow. This vulnerability appears as CVE-2026-74765. The attack may be performed from remote. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Net::IDN::Punycode up to 2.589. This vulnerability affects the function encode_punycode of the component XS backend. The manipulation with an unknown input leads to a integer overflow vulnerability. The CWE definition for the vulnerability is CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Net::IDN::Punycode versions before 2.590 for Perl allow an out-of-bounds read via integer overflow of the delta accumulator in encode_punycode. The XS backend keeps the punycode delta, and the digit index derived from it, in a signed int. The accumulation `delta += (m-n) * (h+1)` has no overflow check, so a large enough code point wraps the delta and the digit index leaves the range of the 36-entry digit table. The bound before the final table access tests only for an index above 36, so a negative index passes it, as does 36 itself. Perl strings hold code points beyond the Unicode range, and one such code point overflows the accumulation on its own. Valid input wraps it as well, for example 1927 ASCII letters followed by U+10FFFF. The conversion functions encode a label before they check its length, so a long label reaches the encoder through the documented API. Only the XS backend is affected. Encoding an attacker-supplied string copies a byte from outside the digit table into the encoded result or crashes the process.

The advisory is available at metacpan.org. This vulnerability was named CVE-2026-74765 since 08/15/2026. The exploitation appears to be easy. The attack can be initiated remotely. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 2.590 eliminates this vulnerability.

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Productinfo

Name

• Net::IDN::Punycode

Version

• 2.589

CPE 2.3info

• 🔒

CPE 2.2info

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