{"id":"UBUNTU-CVE-2026-85644","details":"XS::Parse::Infix versions from 0.40 through 0.49 for Perl treat a number as an array reference. The wrapper function XS::Parse::Infix generates for a list-associative infix operator checks whether arguments are array references, but it tests using SvRV() rather than SvROK(). SvRV() reads a union slot that only holds a referent once SvROK(sv) is true, so the guard never validates that it is a reference. For an IV or NV that slot holds the number itself, SvRV() returns the caller's value and SvTYPE() dereferences it at offset 12. This will generally result in a segmentation fault. An application that hands the wrapper a list built from decoded input (for example, from JSON) lets whoever supplies a number in that list choose the address that the interpreter dereferences. An ordinary string's byte 12 is rarely SVt_PVAV so the guard croaks by luck, but an attacker-crafted string carrying 0x0b there passes, and the buffer is then used as an AV head, with AvARRAY taken from bytes 16-23 and its entries pushed onto the Perl stack as live SVs. A simple proof-of-concept uses the zip operator:     use Syntax::Operator::Zip 'zip';     my @args = ([1], 2);     zip(@args);","modified":"2026-09-30T21:35:21Z","published":"2026-09-28T17:17:00Z","upstream":["CVE-2026-85644"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-85644"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-85644"},{"type":"REPORT","url":"https://lists.security.metacpan.org/cve-announce/msg/43916020/"},{"type":"REPORT","url":"https://metacpan.org/release/PEVANS/XS-Parse-Keyword-0.50/diff/PEVANS/XS-Parse-Keyword-0.49/src/infix.c"},{"type":"REPORT","url":"https://metacpan.org/release/PEVANS/XS-Parse-Keyword-0.50/changes"},{"type":"REPORT","url":"https://metacpan.org/release/PEVANS/XS-Parse-Keyword-0.50/diff/PEVANS/XS-Parse-Keyword-0.49#src/infix.c"},{"type":"REPORT","url":"http://www.openwall.com/lists/oss-security/2026/09/28/14"}],"affected":[{"package":{"name":"libxs-parse-keyword-perl","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/libxs-parse-keyword-perl?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.21-1","0.21-1build1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.21-1build1","binary_name":"libxs-parse-keyword-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85644.json"}},{"package":{"name":"libxs-parse-keyword-perl","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/libxs-parse-keyword-perl?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.38-1","0.39-1","0.39-1build1","0.39-1build2","0.39-1build3"],"ecosystem_specific":{"binaries":[{"binary_name":"libxs-parse-keyword-perl","binary_version":"0.39-1build3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85644.json"}},{"package":{"name":"libxs-parse-keyword-perl","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/libxs-parse-keyword-perl?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.48-2","0.49-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libxs-parse-keyword-perl","binary_version":"0.49-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85644.json"}}],"schema_version":"1.9.0","severity":[{"type":"Ubuntu","score":"medium"}]}