Is CVE-2026-87079 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-87079 being exploited in the wild.

How severe is CVE-2026-87079?

High severity, with a CVSS score of 7.5, published 22 September 2026.

Which products and versions are affected?

CPAN Net::IDN::Punycode before 2.590.

Is there a fix for CVE-2026-87079?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-87079 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-87079?

Check whether you run CPAN Net::IDN::Punycode at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-87079: Net::IDN::Punycode CPU exhaustion via quadratic insertion cost

CVE-2026-87079 · Severity: high · CVSS 7.5 · Published 2026-09-22

Net::IDN::Punycode is a Perl library that decodes internationalized domain names. An attacker can trigger unbounded CPU exhaustion by sending a very long domain label to the decoder, causing it to perform quadratic work. Since the library's Unicode conversion functions do not enforce the DNS 63-byte label limit, a remote attacker can cause denial of service without authentication.

Technologies: CPAN Net::IDN::Punycode. Vendors: CPAN.

Quick answers

Is CVE-2026-87079 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-87079 being exploited in the wild.
How severe is CVE-2026-87079?: High severity, with a CVSS score of 7.5, published 22 September 2026.
Which products and versions are affected?: CPAN Net::IDN::Punycode before 2.590.
Is there a fix for CVE-2026-87079?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-87079 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-87079?: Check whether you run CPAN Net::IDN::Punycode at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability exists in the decode_punycode function in both the XS and pure-Perl backends. The XS backend scans a UTF-8 output buffer from the start for each inserted code point, creating quadratic complexity. The pure-Perl backend has the same issue due to UTF-8 flag handling in substr operations. The domain_to_unicode and uts46_to_unicode functions pass attacker-supplied labels of any length directly to the decoder, bypassing the 63-byte DNS limit check that only applies during ASCII conversion.

Affected products

cpan Net::IDN::Punycode before 2.590

Timeline

2026-09-22: disclosed: CVE-2026-87079 published

References

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