# CVE-2016-15059: libnet-idn-encode-perl: Net::IDN::Punycode versions before 2.301 for Perl allow a heap buffer overflow via unchecked writes past the output b...

CVE-2016-15059 is fixed in libnet-idn-encode-perl on 1 platform, first by DEBIAN-CVE-2016-15059, released September 22, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2016-15059
- Priority: Urgent
- CVSS: 9.8 (critical)
- EPSS: 0.0042
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 22, 2026

## Description

Net::IDN::Punycode versions before 2.301 for Perl allow a heap buffer overflow via unchecked writes past the output buffer in encode_punycode.  The XS backend builds the encoded label in the string buffer of the scalar it returns, sized from the input length. The loop that emits the digits of each code point checks for room before every write, but the write of the last digit of each round and the write of the terminating NUL do not, so an input whose encoded form fills the buffer writes past its end.  Only the XS backend is affected.  Encoding an attacker-supplied string corrupts the heap.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libnet-idn-encode-perl Debian 12.15 (bookworm) | 2.303-1 | [DEBIAN-CVE-2016-15059](https://patchblox.com/security/data/fix/linux/debian-cve-2016-15059.md) | Sep 22, 2026 |
| Linux | libnet-idn-encode-perl Debian 13.5 (trixie) | 2.303-1 | [DEBIAN-CVE-2016-15059](https://patchblox.com/security/data/fix/linux/debian-cve-2016-15059.md) | Sep 22, 2026 |
| Linux | libnet-idn-encode-perl Debian 14 | 2.303-1 | [DEBIAN-CVE-2016-15059](https://patchblox.com/security/data/fix/linux/debian-cve-2016-15059.md) | Sep 22, 2026 |

---

Data as of 2026-11-07T06:34:28Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo