CVE-2026-85644
XS::Parse::Infix versions from 0.40 through 0.49 for Perl treat a number as an array reference
Published Sep 28, 2026
CVSS 3.1 · 7.5 High
EPSS < 1%
KEV · Not listed
Description
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);
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);
Affected Products
-
CVE record
-
NVD configurations
No data
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Red Hat packages
No data
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OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| unaffected |
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No data.
No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Perl | Xs::parse::infix |
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Remediation
Vendor Solution
Upgrade to XS-Parse-Keyword 0.50 or later.
Vendor Workaround
For deployments that cannot upgrade, ensure that correct arguments (only array references where they are expected) are passed to list-associative operators that are defined with XS::Parse::Infix, such as those in Syntax::Operator::Zip.
Tracking
Advisories
| Source | ID | Title |
|---|---|---|
 Ubuntu USN |
USN-8940-1 | Perl XS::Parse::Keyword module vulnerability |
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity Low
Privileges Required None
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact High
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.373% probability within 30 days)
Exploitation none
Automatable yes
Technical Impact partial
References
History
Sep 30, 2026 8:30 PM
Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
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Sep 29, 2026 1:30 PM
First appearance in the feed. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Perl
Perl xs::parse::infix |
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| Vendors & Products |
Perl
Perl xs::parse::infix |
Sep 29, 2026 1:15 PM
Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
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| References |
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| Metrics |
threat_severity
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cvssV3_1
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Sep 28, 2026 7:30 PM
Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| References |
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Sep 28, 2026 4:30 PM
Description updated. Title updated. Weaknesses updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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); | |
| Title | XS::Parse::Infix versions from 0.40 through 0.49 for Perl treat a number as an array reference | |
| Weaknesses | CWE-125 CWE-843 |
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| References |
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