JSON::XS up to 4.4 Decode String decode_str buffer overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.1$0-$5k0.00+

Summaryinfo

A vulnerability was found in JSON::XS up to 4.4. It has been declared as problematic. Affected is the function decode_str of the component Decode String. The manipulation results in buffer overflow. This vulnerability is identified as CVE-2026-124541. The attack can be executed remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in JSON::XS up to 4.4. Affected is the function decode_str of the component Decode String. The manipulation with an unknown input leads to a buffer overflow vulnerability. CWE is classifying the issue as CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer. This is going to have an impact on availability. CVE summarizes:

JSON::XS versions before 4.05 for Perl leak the decoded part of a rejected long string in decode_str. A string is decoded through a fixed-size buffer (16 KiB in 4.04), and each time the buffer fills its contents move into a new scalar. Nothing frees that scalar when the string is then rejected for a control character, an invalid escape, malformed UTF-8 or the end of the input. A process that keeps running after a failed decode retains the decoded part of each rejected string, with its size chosen by the sender. Repeated requests exhaust process memory.

The advisory is shared for download at metacpan.org. This vulnerability is traded as CVE-2026-124541 since 11/08/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available.

Upgrading to version 4.05 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / 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

11/08/2026 CVE reserved
11/14/2026 +6 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-2026-124541 (🔒)

GCVE (CVE): GCVE-0-2026-124541
GCVE (VulDB): GCVE-100-437436

Entryinfo

Created: 11/14/2026 13:15
Changes: 11/14/2026 13:15 (54)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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