CVE-2026-74765
Net::IDN::Punycode versions before 2.590 for Perl allow an out-of-bounds read via integer overflow of the delta accumulator in encode_punycode
Published Sep 22, 2026
CVSS 3.1 · 6.5 Medium
EPSS < 1%
KEV · Not listed
Description
Net::IDN::Punycode versions before 2.590 for Perl allow an out-of-bounds read via integer overflow of the delta accumulator in encode_punycode.
The XS backend keeps the punycode delta, and the digit index derived from it, in a signed int. The accumulation `delta += (m-n) * (h+1)` has no overflow check, so a large enough code point wraps the delta and the digit index leaves the range of the 36-entry digit table. The bound before the final table access tests only for an index above 36, so a negative index passes it, as does 36 itself. Perl strings hold code points beyond the Unicode range, and one such code point overflows the accumulation on its own. Valid input wraps it as well, for example 1927 ASCII letters followed by U+10FFFF. The conversion functions encode a label before they check its length, so a long label reaches the encoder through the documented API.
Only the XS backend is affected.
Encoding an attacker-supplied string copies a byte from outside the digit table into the encoded result or crashes the process.
The XS backend keeps the punycode delta, and the digit index derived from it, in a signed int. The accumulation `delta += (m-n) * (h+1)` has no overflow check, so a large enough code point wraps the delta and the digit index leaves the range of the 36-entry digit table. The bound before the final table access tests only for an index above 36, so a negative index passes it, as does 36 itself. Perl strings hold code points beyond the Unicode range, and one such code point overflows the accumulation on its own. Valid input wraps it as well, for example 1927 ASCII letters followed by U+10FFFF. The conversion functions encode a label before they check its length, so a long label reaches the encoder through the documented API.
Only the XS backend is affected.
Encoding an attacker-supplied string copies a byte from outside the digit table into the encoded result or crashes the process.
Affected Products
-
CVE record
-
NVD configurations
No data
-
Red Hat packages
No data
-
OpenCVE enrichment
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.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Perl | Net::idn::punycode |
|
Remediation
Vendor Solution
Upgrade to Net-IDN-Encode 2.590-TRIAL or later.
Tracking
Advisories
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity Low
Privileges Required None
Scope Unchanged
Confidentiality Impact Low
Integrity Impact None
Availability Impact Low
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.313% probability within 30 days)
Exploitation none
Automatable yes
Technical Impact partial
References
History
Sep 29, 2026 1:30 PM
First appearance in the feed. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Perl
Perl net::idn::punycode |
|
| Vendors & Products |
Perl
Perl net::idn::punycode |
Sep 29, 2026 1:15 PM
Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
Sep 22, 2026 6:30 PM
Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
ssvc
|
Sep 22, 2026 2:30 PM
Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
Sep 22, 2026 7:30 AM
Description updated. Title updated. Weaknesses updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Net::IDN::Punycode versions before 2.590 for Perl allow an out-of-bounds read via integer overflow of the delta accumulator in encode_punycode. The XS backend keeps the punycode delta, and the digit index derived from it, in a signed int. The accumulation `delta += (m-n) * (h+1)` has no overflow check, so a large enough code point wraps the delta and the digit index leaves the range of the 36-entry digit table. The bound before the final table access tests only for an index above 36, so a negative index passes it, as does 36 itself. Perl strings hold code points beyond the Unicode range, and one such code point overflows the accumulation on its own. Valid input wraps it as well, for example 1927 ASCII letters followed by U+10FFFF. The conversion functions encode a label before they check its length, so a long label reaches the encoder through the documented API. Only the XS backend is affected. Encoding an attacker-supplied string copies a byte from outside the digit table into the encoded result or crashes the process. | |
| Title | Net::IDN::Punycode versions before 2.590 for Perl allow an out-of-bounds read via integer overflow of the delta accumulator in encode_punycode | |
| Weaknesses | CWE-125 CWE-190 |
|
| References |
|
|
