Net::IDN::Punycode versions before 2.590 for Perl hang, crash or return a wrong label via unvalidated malformed UTF-8 in encode_punycode
Summary
| CVE | CVE-2026-87082 |
|---|---|
| State | PUBLISHED |
| Assigner | CPANSec |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-22 08:16:40 UTC |
| Updated | 2026-09-22 19:07:00 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.003980000 probability, percentile 0.337990000 (date 2026-09-23)
Problem Types: CWE-835 | CWE-1286 | CWE-835 CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop') | CWE-1286 CWE-1286 Improper Validation of Syntactic Correctness of Input
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
There are no known software configurations currently associated with this CVE in NVD or the CVE Program record.
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/robrwo/Net-IDN-Encode/commit/accb6df57ad107ec0c4bfb27b21551ee... | 9b29abf9-4ab0-4765-b253-1875cd9b441e | github.com | |
| github.com/robrwo/Net-IDN-Encode/commit/572af0183b3a6294e22c6b509268da09... | 9b29abf9-4ab0-4765-b253-1875cd9b441e | github.com | |
| metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes | 9b29abf9-4ab0-4765-b253-1875cd9b441e | metacpan.org | |
| www.openwall.com/lists/oss-security/2026/09/22/17 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | |
| github.com/robrwo/Net-IDN-Encode/commit/0918fb4a951ed5f4494c4cf202419c28... | 9b29abf9-4ab0-4765-b253-1875cd9b441e | github.com | |
| github.com/robrwo/Net-IDN-Encode/commit/59dc7f2c605a897bcbfe0ac5eb2b8dbe... | 9b29abf9-4ab0-4765-b253-1875cd9b441e | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
Additional Advisory Data
Solutions
CNA: Upgrade to Net-IDN-Encode 2.590-TRIAL or later.
There are currently no legacy QID mappings associated with this CVE.