{"id":"CVE-2026-87079","state":"PUBLISHED","title":"Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding a long label in decode_punycode","description":"Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding a long label in decode_punycode.\n\nThe 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.\n\nNothing 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.","publishedAt":"2026-09-22T07:24:47.784Z","updatedAt":"2026-09-22T17:07:28.687Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"CISA-ADP"},"assigner":"CPANSec","products":["Net-IDN-Encode"],"affected":[{"packageName":"Net-IDN-Encode","packageURL":"pkg:cpan/Net-IDN-Encode","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2.590","versionType":"custom"}],"collectionURL":"https://cpan.org/modules","modules":["Net::IDN::Punycode"],"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"}],"references":["https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes","https://github.com/robrwo/Net-IDN-Encode/commit/00d723423b66810af26b88c552bedc61975b3078.patch","https://github.com/robrwo/Net-IDN-Encode/commit/447c6b38ef5d4570329fa4f78690f4e14e09ba0c.patch","http://www.openwall.com/lists/oss-security/2026/09/22/14"],"weaknesses":["CWE-407"],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/87xxx/CVE-2026-87079.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-87079","state":"PUBLISHED","datePublished":"2026-09-22T07:24:47.784Z","dateUpdated":"2026-09-22T17:07:28.687Z","assignerShortName":"CPANSec","assignerOrgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateReserved":"2026-09-08T19:22:20.005Z"},"containers":{"cna":{"title":"Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding a long label in decode_punycode","descriptions":[{"lang":"en","value":"Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding a long label in decode_punycode.\n\nThe 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.\n\nNothing 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."}],"affected":[{"packageName":"Net-IDN-Encode","packageURL":"pkg:cpan/Net-IDN-Encode","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2.590","versionType":"custom"}],"collectionURL":"https://cpan.org/modules","modules":["Net::IDN::Punycode"],"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"}],"references":[{"url":"https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes","tags":["release-notes"]},{"url":"https://github.com/robrwo/Net-IDN-Encode/commit/00d723423b66810af26b88c552bedc61975b3078.patch","tags":["patch"]},{"url":"https://github.com/robrwo/Net-IDN-Encode/commit/447c6b38ef5d4570329fa4f78690f4e14e09ba0c.patch","tags":["patch"]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","description":"CWE-407 Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"CPANSec","orgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateUpdated":"2026-09-22T07:24:47.784Z"},"solutions":[{"lang":"en","value":"Upgrade to Net-IDN-Encode 2.590-TRIAL or later."}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"cpansec-cna-tool 0.1"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-09-22T12:29:30.744292Z","id":"CVE-2026-87079","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-22T12:31:19.170Z"}},{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/09/22/14"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2026-09-22T17:07:28.687Z"}}]}}}