MLEHMANN JSON::XS up to 4.04 Incremental Parser incr_parse out-of-bounds write

CVSS Meta Temp Score
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CTI Interest Score
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6.0$0-$5k0.00+

Summaryinfo

A vulnerability was found in MLEHMANN JSON::XS up to 4.04. It has been rated as critical. Affected by this vulnerability is the function incr_parse of the component Incremental Parser. This manipulation causes out-of-bounds write. This vulnerability is tracked as CVE-2026-129114. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical was found in MLEHMANN JSON::XS up to 4.04. Affected by this vulnerability is the function incr_parse of the component Incremental Parser. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

JSON::XS versions from 3.04 before 4.05 for Perl write one byte past a heap buffer when appending a one-byte chunk in incr_parse. The incremental buffer grows to one and a half times the length it must hold, with no room reserved for the terminating NUL. For an empty buffer and a one-byte chunk that request is one byte, which a buffer whose front was removed by earlier decodes can already have, so nothing is reallocated and the NUL lands one byte past the allocation. A peer streaming data to an incr_parse consumer, choosing how the input is split into reads, can cause a one-byte heap out-of-bounds write.

The advisory is shared at metacpan.org. This vulnerability is known as CVE-2026-129114 since 11/13/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available.

Upgrading to version 4.05 eliminates this vulnerability.

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Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds write
CWE: CWE-787 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: JSON::XS 4.05

Timelineinfo

11/13/2026 CVE reserved
11/14/2026 +1 days Advisory disclosed
11/14/2026 +0 days VulDB entry created
11/14/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: metacpan.org
Status: Confirmed

CNA: CPANSec
CVE: CVE-2026-129114 (🔒)

GCVE (CVE): GCVE-0-2026-129114
GCVE (VulDB): GCVE-100-437437

Entryinfo

Created: 11/14/2026 13:15
Changes: 11/14/2026 13:15 (55)
Complete: 🔍
Cache ID: 216::103

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