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CVE-2026-87079

Net-IDN-Encode · Vulnerability

cve-program · severity unknownCVSS unknownCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-87079

Published

Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding a long label in decode_punycode. The XS backend inserts each decoded code point into a UTF-8 buffer and finds the insertion point by scanning that buffer from the start, one character at a time. The scan runs once per code point over the output built so far, so the cost is quadratic in the label length. The pure-Perl backend downgrades its input to bytes so that substr can index it directly, but takes its working copy before the downgrade, so when the input carries the UTF-8 flag every substr on the copy scans from the start, with the same quadratic cost. Nothing bounds the label length in the to-Unicode direction. The 63-byte DNS limit is checked only when converting to ASCII, so domain_to_unicode and uts46_to_unicode pass an attacker-supplied label of any length to the decoder.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-87079

Published

Net-IDN-Encode

https://cpan.org/modules

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "collectionURL": "https://cpan.org/modules",
                    "defaultStatus": "unaffected",
                    "modules": [
                        "Net::IDN::Punycode"
                    ],
                    "packageName": "Net-IDN-Encode",
                    "packageURL": "pkg:cpan/Net-IDN-Encode",
                    "programFiles": [
                        "lib/Net/IDN/Punycode.xs",
                        "lib/Net/IDN/Punycode/PP.pm"
                    ],
                    "programRoutines": [
                        {
                            "name": "Net::IDN::Punycode::decode_punycode"
                        },
                        {
                            "name": "Net::IDN::Punycode::PP::decode_punycode"
                        }
                    ],
                    "repo": "https://github.com/robrwo/Net-IDN-Encode",
                    "versions": [
                        {
                            "lessThan": "2.590",
                            "status": "affected",
                            "version": "0",
                            "versionType": "custom"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON