CVE-2026-87079 Affecting libnet-idn-encode-perl package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-DEBIAN13-LIBNETIDNENCODEPERL-20044738
- published22 Sept 2026
- disclosed22 Sept 2026
Introduced: 22 Sep 2026
NewCVE-2026-87079 (opens in a new tab)How to fix?
There is no fixed version for Debian:13 libnet-idn-encode-perl.
NVD Description
Note: Versions mentioned in the description apply only to the upstream libnet-idn-encode-perl package and not the libnet-idn-encode-perl package as distributed by Debian.
See How to fix? for Debian:13 relevant fixed versions and status.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-87079
- https://github.com/robrwo/Net-IDN-Encode/commit/00d723423b66810af26b88c552bedc61975b3078.patch
- https://github.com/robrwo/Net-IDN-Encode/commit/447c6b38ef5d4570329fa4f78690f4e14e09ba0c.patch
- https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes
- http://www.openwall.com/lists/oss-security/2026/09/22/14