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CVE-2026-87082

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode

7.5 HighFix available

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode.

Neither backend checks that its input is well-formed UTF-8, so a string with the UTF-8 flag set over malformed bytes, as the :utf8 PerlIO layer produces from any malformed input, reaches the encoder unchecked. On perl 5.32 and later the XS backend reports a malformed sequence with a length of (STRLEN)-1, so the scan steps back one byte instead of forward and never ends. On earlier perls the XS returns a valid label for a different name. The pure-Perl backend runs a regex over the flagged string. Depending on the bytes, it aborts with SIGBUS on perl 5.28 and later, dies with a panic, or returns a wrong label.

The documented conversion functions match the label against Unicode properties first and that match dies on such a string, so only a direct call to encode_punycode reaches the defect. The decoder is not affected.

A direct caller encoding attacker-supplied bytes hangs, crashes or gets a label for a name the input never held.

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

0.42%Up 0.3 points since Sep 22, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.5

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode.

Neither backend checks that its input is well-formed UTF-8, so a string with the UTF-8 flag set over malformed bytes, as the :utf8 PerlIO layer produces from any malformed input, reaches the encoder unchecked. On perl 5.32 and later the XS backend reports a malformed sequence with a length of (STRLEN)-1, so the scan steps back one byte instead of forward and never ends. On earlier perls the XS returns a valid label for a different name. The pure-Perl backend runs a regex over the flagged string. Depending on the bytes, it aborts with SIGBUS on perl 5.28 and later, dies with a panic, or returns a wrong label.

The documented conversion functions match the label against Unicode properties first and that match dies on such a string, so only a direct call to encode_punycode reaches the defect. The decoder is not affected.

A direct caller encoding attacker-supplied bytes hangs, crashes or gets a label for a name the input never held.

Record
CVE-2026-87082
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-835, CWE-1286
Updated
2026-11-02
EUVDEUVD-2026-84295 7.5

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode.

Neither backend checks that its input is well-formed UTF-8, so a string with the UTF-8 flag set over malformed bytes, as the :utf8 PerlIO layer produces from any malformed input, reaches the encoder unchecked. On perl 5.32 and later the XS backend reports a malformed sequence with a length of (STRLEN)-1, so the scan steps back one byte instead of forward and never ends. On earlier perls the XS returns a valid label for a different name. The pure-Perl backend runs a regex over the flagged string. Depending on the bytes, it aborts with SIGBUS on perl 5.28 and later, dies with a panic, or returns a wrong label.

The documented conversion functions match the label against Unicode properties first and that match dies on such a string, so only a direct call to encode_punycode reaches the defect. The decoder is not affected.

A direct caller encoding attacker-supplied bytes hangs, crashes or gets a label for a name the input never held.

Record
EUVD-2026-84295
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-4v8j-337r-265v 7.5

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via...

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode.

Neither backend checks that its input is well-formed UTF-8, so a string with the UTF-8 flag set over malformed bytes, as the :utf8 PerlIO layer produces from any malformed input, reaches the encoder unchecked. On perl 5.32 and later the XS backend reports a malformed sequence with a length of (STRLEN)-1, so the scan steps back one byte instead of forward and never ends. On earlier perls the XS returns a valid label for a different name. The pure-Perl backend runs a regex over the flagged string. Depending on the bytes, it aborts with SIGBUS on perl 5.28 and later, dies with a panic, or returns a wrong label.

The documented conversion functions match the label against Unicode properties first and that match dies on such a string, so only a direct call to encode_punycode reaches the defect. The decoder is not affected.

A direct caller encoding attacker-supplied bytes hangs, crashes or gets a label for a name the input never held.

Record
GHSA-4v8j-337r-265v
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-835
Updated
2026-11-02
NVD 7.5

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode.

Neither backend checks that its input is well-formed UTF-8, so a string with the UTF-8 flag set over malformed bytes, as the :utf8 PerlIO layer produces from any malformed input, reaches the encoder unchecked. On perl 5.32 and later the XS backend reports a malformed sequence with a length of (STRLEN)-1, so the scan steps back one byte instead of forward and never ends. On earlier perls the XS returns a valid label for a different name. The pure-Perl backend runs a regex over the flagged string. Depending on the bytes, it aborts with SIGBUS on perl 5.28 and later, dies with a panic, or returns a wrong label.

The documented conversion functions match the label against Unicode properties first and that match dies on such a string, so only a direct call to encode_punycode reaches the defect. The decoder is not affected.

A direct caller encoding attacker-supplied bytes hangs, crashes or gets a label for a name the input never held.

Record
CVE-2026-87082
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-835, CWE-1286
Updated
2026-11-02
OSV 7.5

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode.

Neither backend checks that its input is well-formed UTF-8, so a string with the UTF-8 flag set over malformed bytes, as the :utf8 PerlIO layer produces from any malformed input, reaches the encoder unchecked. On perl 5.32 and later the XS backend reports a malformed sequence with a length of (STRLEN)-1, so the scan steps back one byte instead of forward and never ends. On earlier perls the XS returns a valid label for a different name. The pure-Perl backend runs a regex over the flagged string. Depending on the bytes, it aborts with SIGBUS on perl 5.28 and later, dies with a panic, or returns a wrong label.

The documented conversion functions match the label against Unicode properties first and that match dies on such a string, so only a direct call to encode_punycode reaches the defect. The decoder is not affected.

A direct caller encoding attacker-supplied bytes hangs, crashes or gets a label for a name the input never held.

Record
CVE-2026-87082
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-1286, CWE-835
Updated
2026-11-07
OSVDEBIAN-CVE-2026-87082 7.5

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode. Neither backend checks that its input is well-formed UTF-8, so a string with the UTF-8 flag set over malformed bytes, as the :utf8 PerlIO layer produces from any malformed input, reaches the encoder unchecked. On perl 5.32 and later the XS backend reports a malformed sequence with a length of (STRLEN)-1, so the scan steps back one byte instead of forward and never ends. On earlier perls the XS returns a valid label for a different name. The pure-Perl backend runs a regex over the flagged string. Depending on the bytes, it aborts with SIGBUS on perl 5.28 and later, dies with a panic, or returns a wrong label. The documented conversion functions match the label against Unicode properties first and that match dies on such a string, so only a direct call to encode_punycode reaches the defect. The decoder is not affected. A direct caller encoding attacker-supplied bytes hangs, crashes or gets a label for a name the input never held.

Record
DEBIAN-CVE-2026-87082
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-2026-87082 7.5

Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode. Neither backend checks that its input is well-formed UTF-8, so a string with the UTF-8 flag set over malformed bytes, as the :utf8 PerlIO layer produces from any malformed input, reaches the encoder unchecked. On perl 5.32 and later the XS backend reports a malformed sequence with a length of (STRLEN)-1, so the scan steps back one byte instead of forward and never ends. On earlier perls the XS returns a valid label for a different name. The pure-Perl backend runs a regex over the flagged string. Depending on the bytes, it aborts with SIGBUS on perl 5.28 and later, dies with a panic, or returns a wrong label. The documented conversion functions match the label against Unicode properties first and that match dies on such a string, so only a direct call to encode_punycode reaches the defect. The decoder is not affected. A direct caller encoding attacker-supplied bytes hangs, crashes or gets a label for a name the input never held.

Record
UBUNTU-CVE-2026-87082
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-2026-87082 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 0.42%, the 36th percentile. Fixed in libnet-idn-encode-perl 2.600-1.

References

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