{"id":"CVE-2026-87079","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.\n\nThe XS backend inserts each decoded code point into a UTF-8 buffer and finds the insertio…","summary":"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 insertio…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-407"],"product":"Net-IDN-Encode","affected":["Net-IDN-Encode < 2.590"],"published":"2026-09-22","updated":"2026-09-22","sourceUpdated":"2026-09-22T19:07:00.983","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-87079","references":[{"url":"https://github.com/robrwo/Net-IDN-Encode/commit/00d723423b66810af26b88c552bedc61975b3078.patch","label":"9b29abf9-4ab0-4765-b253-1875cd9b441e"},{"url":"https://github.com/robrwo/Net-IDN-Encode/commit/447c6b38ef5d4570329fa4f78690f4e14e09ba0c.patch","label":"9b29abf9-4ab0-4765-b253-1875cd9b441e"},{"url":"https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes","label":"9b29abf9-4ab0-4765-b253-1875cd9b441e"},{"url":"http://www.openwall.com/lists/oss-security/2026/09/22/14","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-22T12:29:30.744292Z"},"ingestedAt":"2026-09-22T08:00:27.699Z","epss":0.0063,"epssPercentile":0.47902,"slug":"CVE-2026-87079","body":"## Overview\n\nNet::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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":209032,"id":"CVE-2026-87079","ts":1790082254285,"field":"cvss","old":null,"new":"7.5"},{"seq":209031,"id":"CVE-2026-87079","ts":1790082254285,"field":"severity","old":"none","new":"high"}]}