Access of Resource Using Incompatible Type ('Type Confusion') The advisory has been revoked - it doesn't affect any version of package perl-XS-Parse-Keyword-Builder  (opens in a new tab)

The Centos security team deemed this advisory irrelevant for Centos:10.

Note: Versions mentioned in the description apply only to the upstream perl-XS-Parse-Keyword-Builder package and not the perl-XS-Parse-Keyword-Builder package as distributed by Centos.

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);

• https://bugzilla.redhat.com/show_bug.cgi?id=2542563
• https://access.redhat.com/security/cve/CVE-2026-85644
• 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
• http://www.openwall.com/lists/oss-security/2026/09/28/14