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9.1
CVE-2026-87078: Perl libnet-idn-encode-perl can waste memory on bad input
CVE-2026-87078 · published 7 days ago
Summary
The libnet-idn-encode-perl library (versions 2.302 through 2.589) on Debian may keep memory allocated every time it encounters an invalid part of a domain name. Over time, this can cause the program to use more and more memory, potentially affecting performance. Upgrade the library to version 2.590 or later to stop the memory leak.
What to do
The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| Debian:12 | debian | libnet-idn-encode-perl | All versions |
| Ubuntu:16.04:LTS | canonical | libnet-idn-encode-perl | All versions |
Original advisory text
Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode
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.
References
- https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes Third Party Advisory
- https://github.com/robrwo/Net-IDN-Encode/commit/92572f726e48af5559de4cc8a831463b... Third Party Advisory
- https://github.com/robrwo/Net-IDN-Encode/commit/edad63e0eeeeb18d93bc6dfe4d9dcdff... Third Party Advisory
- https://security-tracker.debian.org/tracker/CVE-2026-87078 Vendor Advisory
- http://www.openwall.com/lists/oss-security/2026/09/22/13 URL
- https://cpan.org/modules URL
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/87xxx/CVE-2026-87078... Vendor Advisory
- https://github.com/robrwo/Net-IDN-Encode Product
- https://nvd.nist.gov/vuln/detail/CVE-2026-87078 Vendor Advisory
- https://ubuntu.com/security/CVE-2026-87078 Third Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-87078 Third Party Advisory
- https://lists.security.metacpan.org/cve-announce/msg/43753020/ Third Party Advisory
Severity
9.1
Critical
Exploitation
EPSS <1%
Type
CWE-401Memory Leak
Timeline
Published22 Sep 2026
Updated27 Sep 2026
First seen22 Sep 2026
Sources
CVE-2026-87078 · NVD
CVE-2026-87078 · MITRE
DEBIAN-CVE-2026-87078 · OSV
CVE-2026-87078 · OSV
UBUNTU-CVE-2026-87078 · OSV
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