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Fencer Vulns
high 7.5

CVE-2026-85644 json

XS::Parse::Infix versions from 0.40 through 0.49 for Perl treat a number as an array reference

published 2026-09-28 41 d ago modified 2026-09-30 39 d ago also EUVD-2026-88344

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

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);

Patch / fix

  • libxs-parse-keyword-perl Debian 14 0.51-1

debian advisories DEBIAN-CVE-2026-85644

  • libxs-parse-keyword-perl Ubuntu 26.10 0.49-1ubuntu1
  • libxs-parse-keyword-perl Ubuntu 26.04 LTS 0.49-1ubuntu0.1

ubuntu advisories UBUNTU-CVE-2026-85644

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • perl-XS-Parse-Keyword SLES for SAP applications 16.0, SLES 16.0 0.480.0-160000.3.1

suse advisories SUSE-SU-2026:24244-1

  • perl-XS-Parse-Keyword openSUSE Leap 16.0 0.480.0-160000.3.1
  • perl-XS-Parse-Keyword openSUSE Tumbleweed 0.500.0-1.1

opensuse advisories openSUSE-SU-2026:22101-1openSUSE-SU-2026:11863-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-85644 updated cvss 7.5

perl-XS-Parse-Keyword: perl-XS-Parse-Keyword: Denial of Service via improper array reference validation

  • Red Hat Enterprise Linux 10 perl-XS-Parse-Keyword 0.39-8.el10
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
39 d ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Classification

Weakness
  • CWE-843 Access of Resource Using Incompatible Type
  • CWE-125 Out-of-bounds Read

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.