Vulnerability Description
Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode. The XS backend allocates the scalar it returns before it validates the input, sizing the buffer at twice the input length. The scalar is released only on the success path, so each of the three croaks that reject a label leaves the scalar and its buffer allocated. Nothing bounds the label length in the to-Unicode direction, since the 63-byte DNS limit is checked only when converting to ASCII. Only the XS backend is affected. A sender who supplies invalid labels grows the process by twice the label length per rejected call, with no successful call needed.
CVSS Score
CRITICAL
Related Weaknesses (CWE)
References
- https://github.com/robrwo/Net-IDN-Encode/commit/92572f726e48af5559de4cc8a831463b
- https://github.com/robrwo/Net-IDN-Encode/commit/edad63e0eeeeb18d93bc6dfe4d9dcdff
- https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes
- http://www.openwall.com/lists/oss-security/2026/09/22/13
FAQ
What is CVE-2026-87078?
CVE-2026-87078 is a vulnerability with a CVSS score of 9.1 (CRITICAL). Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode. The XS backend allocates the scalar it returns before it validates the ...
How severe is CVE-2026-87078?
CVE-2026-87078 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-87078?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.