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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

Quick assessment

Affected
CVE-2026-87079
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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

EPSS 0.15% · P5

Affected Version Matrix 1

VendorProduct Version RangeStatus
None None < 2.590 affected

I. Basic Information for CVE-2026-87079

Vulnerability Information

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Vulnerability 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
Source: CVE Program / CVE List V5
Vulnerability 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 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
算法复杂性
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
- - 0 ~ 2.590 -

II. Public POCs for CVE-2026-87079

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III. Intelligence Information for CVE-2026-87079

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Patches & Fixes for CVE-2026-87079 (2)

Other References for CVE-2026-87079 (1)

IV. Related Vulnerabilities

Same weakness: CWE-407

V. Comments for CVE-2026-87079

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