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CRITICAL

CVE-2026-87078

CVSS v3

9.1

CRITICAL

EPSS Score

0.7 %

exploit probability, as of 2026-09-28

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode. The XS backend allocates the scalar it returns before it validates the input, sizing the buffer at twice the input length. The scalar is released only on the success path, so each of the three croaks that reject a label leaves the scalar and its buffer allocated. Nothing bounds the label length in the to-Unicode direction, since the 63-byte DNS limit is checked only wh

Technical details

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

Frequently asked questions

What is CVE-2026-87078?

Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode. The XS backend allocates the scalar it returns before it validates the input, sizing the buffer at twice the input length. The scalar is released only on the success path, so each of the three croaks that reject a label leaves the scalar and its buffer allocated. Nothing bounds the label length in the to-Unicode direction, since the 63-byte DNS limit is checked only wh

Is CVE-2026-87078 actively exploited?

Active exploitation of CVE-2026-87078 has not been confirmed. Its EPSS score was 0.7% on 2026-09-28, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-87078?

CVE-2026-87078 has a CVSS v3 base score of 9.1 (CRITICAL severity).

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