---
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: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-125
  - CWE-843
vendor: Red Hat
product: XS-Parse-Keyword
affected:
  - XS-Parse-Keyword >= 0.40 <= 0.49
published: '2026-09-28'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T20:17:34.993'
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
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/28/14'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-85644.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-85644'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2542563'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-85644'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-85644'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-30T19:50:11.084770Z'
epss: 0.00373
epssPercentile: 0.31112
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.

## Vendor advisories

- **Red Hat VEX** · Important · updated 2026-10-05 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-85644.json)