---
id: CVE-2026-85644
title: >-
  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 …
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 …
severity: none
cwe:
  - CWE-125
  - CWE-843
product: XS-Parse-Keyword
affected:
  - XS-Parse-Keyword >= 0.40 <= 0.49
published: '2026-09-28'
updated: '2026-09-28'
sourceUpdated: '2026-09-28T17:17:51.127'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-85644'
references:
  - url: 'https://metacpan.org/release/PEVANS/XS-Parse-Keyword-0.50/changes'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: >-
      https://metacpan.org/release/PEVANS/XS-Parse-Keyword-0.50/diff/PEVANS/XS-Parse-Keyword-0.49#src/infix.c
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-28T17:16:27.816Z'
---

## Overview

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);

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.