libnet-idn-encode-perl — security advisory
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.
- Products
- libnet-idn-encode-perl
- Affected versions
- 2.202-1, 2.300-1, 2.300-1build1, 2.400-1build1, 2.500-1, 2.500-1build1, 2.500-1build2, 2.500-2, 2.500-2build1, 2.500-3, 2.500-3build1, 2.500-3build2, 2.500-5, 2.500-5build1, 2.500-5build2
- Fixed versions
- Not specified
- CVEs
- CVE-2026-87082
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:24 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-87082
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
Complete source record
{
"id": "e730a3de8c73328283ef1cc77e4cac24ffda74178b08b160edd0140176d69f67",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-87082",
"method": "structured",
"payload": {
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"title": "UBUNTU-CVE-2026-87082",
"summary": "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.",
"evidence": "osv:UBUNTU-CVE-2026-87082",
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"modified": "2026-10-17T13:01:14.264342014Z",
"provider": "osv",
"upstream": [
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"references": [
"https://ubuntu.com/security/CVE-2026-87082",
"https://www.cve.org/CVERecord?id=CVE-2026-87082",
"https://lists.security.metacpan.org/cve-announce/msg/43753021/",
"https://github.com/robrwo/Net-IDN-Encode/commit/0918fb4a951ed5f4494c4cf202419c2842507ea4.patch",
"https://github.com/robrwo/Net-IDN-Encode/commit/572af0183b3a6294e22c6b509268da09697cf77d.patch",
"https://github.com/robrwo/Net-IDN-Encode/commit/59dc7f2c605a897bcbfe0ac5eb2b8dbe6792348d.patch",
"https://github.com/robrwo/Net-IDN-Encode/commit/accb6df57ad107ec0c4bfb27b21551eed97c700e.patch",
"https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes"
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"source_id": "core-osv",
"document_id": 361341,
"published_at": "2026-09-22T08:16:00+00:00"
}