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CVE-2026-87081

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii

7.5 HighFix available

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii.

to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.38%Up 0.2 points since Sep 22, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.5

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii.

to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.

Record
CVE-2026-87081
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-407
Updated
2026-11-02
EUVDEUVD-2026-84294 7.5

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii.

to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.

Record
EUVD-2026-84294
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-653x-rhrr-h9h8 7.5

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode...

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii.

to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.

Record
GHSA-653x-rhrr-h9h8
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-407
Updated
2026-11-02
NVD 7.5

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii.

to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.

Record
CVE-2026-87081
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-407
Updated
2026-11-02
OSV 7.5

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii.

to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.

Record
CVE-2026-87081
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-407
Updated
2026-11-07
OSVDEBIAN-CVE-2026-87081 7.5

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii. to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.

Record
DEBIAN-CVE-2026-87081
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-03
OSVUBUNTU-CVE-2026-87081 7.5

Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii. to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.

Record
UBUNTU-CVE-2026-87081
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2026:12468-1 No score

perl-Net-IDN-Encode-2.600.0-1.1 on GA media

These are all security issues fixed in the perl-Net-IDN-Encode-2.600.0-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:12468-1
Updated
2026-11-07

Affected packages

Affected packages
PackageAffectedFixed
libnet-idn-encode-perl
Debian:12
All versions, plus listed versions
2.500-32.500-52.502-12.600-1
None known
libnet-idn-encode-perl
Debian:13
All versions, plus listed versions
2.500-52.502-12.600-1
None known
libnet-idn-encode-perl
Debian:14
before 2.600-1, plus listed versions
2.500-52.502-1
2.600-1
libnet-idn-encode-perl
Ubuntu:16.04:LTS
All versions, plus listed versions
2.202-12.300-12.300-1build1
None known
libnet-idn-encode-perl
Ubuntu:18.04:LTS
All versions, plus listed versions
2.400-1build1
None known
libnet-idn-encode-perl
Ubuntu:20.04:LTS
All versions, plus listed versions
2.500-12.500-1build1
None known
libnet-idn-encode-perl
Ubuntu:22.04:LTS
All versions, plus listed versions
2.500-1build22.500-22.500-2build1
None known
libnet-idn-encode-perl
Ubuntu:24.04:LTS
All versions, plus listed versions
2.500-32.500-3build12.500-3build22.500-5
None known
libnet-idn-encode-perl
Ubuntu:26.10
All versions, plus listed versions
2.500-5build12.500-5build2
None known
libnet-idn-encode-perl
Ubuntu:26.04:LTS
All versions, plus listed versions
2.500-5build1
None known
perl-Net-IDN-Encode
openSUSE:Tumbleweed
From an advisory covering 7 CVEs
before 2.600.0-1.1
2.600.0-1.1

History

History
RecordedChangedSources
affected, aliases, referencesOSV
factsOSV
affected, factsOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-87081 is a high vulnerability (CVSS 7.5) in libnet-idn-encode-perl, published September 22, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.38%, the 32nd percentile. Fixed in libnet-idn-encode-perl 2.600-1.

References

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