{"id":"UBUNTU-CVE-2026-19566","details":"Net::CIDR::Set versions before 0.23 for Perl allow memory exhaustion and malformed set ranges via unbounded IPv6 prefix lengths. The _encode method accepts any prefix length matching `(0|[1-9][0-9]*)` and passes it to _width2bits(), which builds the mask as `'1' x ($width + 8)`, one character per bit. The _inc() method then unpacks the packed mask into a Perl array of one scalar per byte, so the prefix length alone sets the allocation size: `::/100000000` builds a 100 MB string and a 12.5 million element array. The value being tested is parsed, not just the configured ranges: contains() builds a set from its argument, and _guess_coder() tries the IPv4 coder and then the IPv6 coder, so an IPv4-only set expands an oversized IPv6 prefix length before the mixed address width check rejects it. Any caller that passes untrusted input to contains() or add() can exhaust process memory. A prefix length above 128 is also stored as a range that does not match the requested block: 2001:db8::/129 stringifies back unchanged, contains() of its own base address returns false, and removing it from a set drops the base address while the set still prints as covering it.","modified":"2026-08-19T11:01:27Z","published":"2026-08-12T09:17:00Z","upstream":["CVE-2026-19566"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-19566"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-19566"},{"type":"REPORT","url":"https://lists.security.metacpan.org/cve-announce/msg/42620063/"},{"type":"REPORT","url":"https://github.com/robrwo/perl-Net-CIDR-Set/security/advisories/GHSA-grjr-r4x5-mx4p"},{"type":"REPORT","url":"https://github.com/robrwo/perl-Net-CIDR-Set/commit/e16b27db676fd1ca671fbb31208a22c1b1ba9724.patch"},{"type":"REPORT","url":"https://metacpan.org/release/RRWO/Net-CIDR-Set-0.23/changes"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-49942"}],"affected":[{"package":{"name":"libnet-cidr-set-perl","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/libnet-cidr-set-perl?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.13-2"],"ecosystem_specific":{"binaries":[{"binary_name":"libnet-cidr-set-perl","binary_version":"0.13-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19566.json"}},{"package":{"name":"libnet-cidr-set-perl","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/libnet-cidr-set-perl?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.13-3"],"ecosystem_specific":{"binaries":[{"binary_name":"libnet-cidr-set-perl","binary_version":"0.13-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19566.json"}},{"package":{"name":"libnet-cidr-set-perl","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/libnet-cidr-set-perl?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.13-4","0.13-5"],"ecosystem_specific":{"binaries":[{"binary_version":"0.13-5","binary_name":"libnet-cidr-set-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19566.json"}},{"package":{"name":"libnet-cidr-set-perl","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/libnet-cidr-set-perl?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.19-1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.19-1","binary_name":"libnet-cidr-set-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19566.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}