CVE-2026-88358
Received Received - Intake

Heap Out-of-Bounds Read in simdjson

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: MITRE

Description
simdjson 4.6.1 contains a one-byte out-of-bounds read vulnerability in dom::parser::parse_unpadded(). A specially crafted truncated JSON document whose final structural token closes a nested array or object can cause json_iterator::walk_document() to access buf[len] after the input buffer has been exhausted. This results in a heap out-of-bounds read and may cause application termination, leading to denial of service.

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Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-24
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-88358
EUVD
EUVD-2026-86284

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
simdjson simdjson 4.6.1

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

CVE-2026-88358 is a one-byte out-of-bounds heap read in the simdjson library's parse_unpadded() function. It occurs when processing truncated JSON documents with nested closing brackets like [[] or {"a":{. The parser reads one byte past the buffer end in json_iterator::walk_document(), causing a heap-buffer-overflow. This can crash applications and lead to denial of service.

Detection Guidance

To detect this vulnerability, use AddressSanitizer (ASan) with a test JSON input like '[[]' or '{"a":{}' to trigger the heap-buffer-overflow. Compile simdjson with ASan and run: ./your_application '[[}' or similar truncated JSON inputs.

Impact Analysis

This vulnerability may cause applications using simdjson to crash or terminate unexpectedly when parsing malformed JSON input. This leads to denial of service for services relying on the library. Attackers could exploit this by sending specially crafted JSON data to trigger the out-of-bounds read.

Mitigation Strategies

Update to the latest version of simdjson that includes the fix for CVE-2026-88358. If updating is not possible, avoid using the unpadded parse API (parse_unpadded) and switch to padded parsing methods.

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