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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| unaffected |
|
No data.
No data.
OpenCVE Enrichment is a feature of OpenCVE that uses AI to automatically link vendors and products to CVEs. Learn more on GitHub.
No data.
Project Subscriptions
No data.
No advisories yet.
Solution
Upgrade to Net-IDN-Encode 2.590-TRIAL or later.
Workaround
No workaround given by the vendor.
Tue, 22 Sep 2026 18:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Tue, 22 Sep 2026 13:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
Tue, 22 Sep 2026 07:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| 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 | |
| Weaknesses | CWE-407 | |
| References |
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-09-22T17:07:28.687Z
Reserved: 2026-09-08T19:22:20.005Z
Link: CVE-2026-87079
Vulnrichment
Updated: 2026-09-22T17:07:28.687Z
NVD
Status : Received
Published: 2026-09-22T08:16:40.637
Modified: 2026-09-22T18:17:24.850
Link: CVE-2026-87079
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-09-22T15:45:17Z