libxs-parse-keyword-perl — security advisory

{
  "id": "171b458e46d5bc474b4c5ff226be1168650c15e64e3d9779e6eb9abd6ce4a126",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-85644",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-85644",
    "summary": "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);",
    "evidence": "osv:UBUNTU-CVE-2026-85644",
    "products": [
      {
        "name": {
          "value": "libxs-parse-keyword-perl",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.49-1ubuntu1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "0.49-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.49-1build1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "libxs-parse-keyword-perl",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.49-1ubuntu0.1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "0.48-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "0.49-1",
            "evidence": "/affected/1/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "UBUNTU-CVE-2026-85644",
      "aliases": [
        "UBUNTU-CVE-2026-85644"
      ],
      "metrics": [
        {
          "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0.49-1ubuntu1"
                }
              ]
            }
          ],
          "package": {
            "name": "libxs-parse-keyword-perl",
            "purl": "pkg:deb/ubuntu/libxs-parse-keyword-perl?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "0.49-1",
            "0.49-1build1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85644.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "libxs-parse-keyword-perl",
                "binary_version": "0.49-1ubuntu1"
              }
            ],
            "availability": "No subscription required"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0.49-1ubuntu0.1"
                }
              ]
            }
          ],
          "package": {
            "name": "libxs-parse-keyword-perl",
            "purl": "pkg:deb/ubuntu/libxs-parse-keyword-perl?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "0.48-2",
            "0.49-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85644.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "libxs-parse-keyword-perl",
                "binary_version": "0.49-1ubuntu0.1"
              }
            ],
            "availability": "No subscription required"
          }
        }
      ],
      "modified": "2026-10-21T04:30:02.767002773Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-85644"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-85644",
        "https://www.cve.org/CVERecord?id=CVE-2026-85644",
        "https://lists.security.metacpan.org/cve-announce/msg/43916020/",
        "https://metacpan.org/release/PEVANS/XS-Parse-Keyword-0.50/diff/PEVANS/XS-Parse-Keyword-0.49/src/infix.c",
        "https://metacpan.org/release/PEVANS/XS-Parse-Keyword-0.50/changes",
        "https://metacpan.org/release/PEVANS/XS-Parse-Keyword-0.50/diff/PEVANS/XS-Parse-Keyword-0.49#src/infix.c",
        "https://ubuntu.com/security/notices/USN-8940-1"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-85644",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 391585,
  "published_at": "2026-09-28T17:17:00+00:00"
}