CVE-2026-129114
Received
Received - Intake
Heap Buffer Overflow in JSON::XS Perl Module
Vulnerability report for CVE-2026-129114, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-11-14
Last updated on: 2026-11-14
Assigner: CPANSec
Description
Description
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.
CVSS Scores
EPSS Scores
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Meta Information
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-193 | A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value. |
| CWE-122 | A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). |
