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HIGH

CVE-2026-87079

CVSS v3

7.5

HIGH

EPSS Score

0.6 %

exploit probability, as of 2026-09-28

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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. 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

Technical details

Published
2026-09-22
Last Modified
2026-09-22

Frequently asked questions

What is CVE-2026-87079?

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

Is CVE-2026-87079 actively exploited?

Active exploitation of CVE-2026-87079 has not been confirmed. Its EPSS score was 0.6% on 2026-09-28, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-87079?

CVE-2026-87079 has a CVSS v3 base score of 7.5 (HIGH severity).

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