# CVE-2026-74765: libnet-idn-encode-perl: Net::IDN::Punycode versions before 2.590 for Perl allow an out-of-bounds read via integer overflow of the delta accum...

CVE-2026-74765 is fixed in 4 products on 1 platform, first by DEBIAN-CVE-2026-74765, released September 22, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-74765
- Priority: Routine
- CVSS: 6.5 (medium)
- EPSS: 0.0033
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 22, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libnet-idn-encode-perl Debian 14 | 2.600-1 | [DEBIAN-CVE-2026-74765](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74765.md) | Sep 22, 2026 |
| Linux | perl-Net-IDN-Encode Fedora 43 | 2.502-1.fc43 | [FEDORA-2026-4AEC7019EB](https://patchblox.com/security/data/fix/linux/fedora-2026-4aec7019eb.md) | Nov 7, 2026 |
| Linux | perl-Net-IDN-Encode amzn 2023 | 2.590-1.amzn2023.0.1 | [ALAS2023-2026-3190](https://patchblox.com/security/data/fix/linux/alas2023-2026-3190.md) | Nov 7, 2026 |
| Linux | perl-Net-IDN-Encode-debuginfo Fedora 43 | 2.502-1.fc43 | [FEDORA-2026-4AEC7019EB](https://patchblox.com/security/data/fix/linux/fedora-2026-4aec7019eb.md) | Nov 7, 2026 |
| Linux | perl-Net-IDN-Encode-debuginfo amzn 2023 | 2.590-1.amzn2023.0.1 | [ALAS2023-2026-3190](https://patchblox.com/security/data/fix/linux/alas2023-2026-3190.md) | Nov 7, 2026 |
| Linux | perl-Net-IDN-Encode-debugsource Fedora 43 | 2.502-1.fc43 | [FEDORA-2026-4AEC7019EB](https://patchblox.com/security/data/fix/linux/fedora-2026-4aec7019eb.md) | Nov 7, 2026 |
| Linux | perl-Net-IDN-Encode-debugsource amzn 2023 | 2.590-1.amzn2023.0.1 | [ALAS2023-2026-3190](https://patchblox.com/security/data/fix/linux/alas2023-2026-3190.md) | Nov 7, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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