Heap buffer overflow via wrapped escape counter
Published Jul 27, 2026 · Updated Jul 27, 2026
Heap buffer overflow in cJSON 1.7.19 on 32-bit platforms allows attackers to corrupt memory via crafted JSON string printing. In print_string_ptr() in cJSON.c, the 32-bit escape_characters size_t wraps after roughly 858,993,460 control characters, underallocating the output buffer before the write loop overruns it. Reachability requires a 32-bit build and an application path that prints attacker-controlled strings with cJSON_PrintBuffered(); CERT.PL has not demonstrated code execution, disclosure, or a specific denial-of-service mode.
Summary
What happened
Heap buffer overflow in cJSON 1.7.19 on 32-bit platforms allows attackers to corrupt memory via crafted JSON string printing. In print_string_ptr() in cJSON.c, the 32-bit escape_characters size_t wraps after roughly 858,993,460 control characters, underallocating the output buffer before the write loop overruns it. Reachability requires a 32-bit build and an application path that prints attacker-controlled strings with cJSON_PrintBuffered(); CERT.PL has not demonstrated code execution, disclosure, or a specific denial-of-service mode.
The record
- CVE
- CVE-2026-16554
- Published
- Jul 27, 2026
- Updated
- Jul 27, 2026
- Vendor
- cJSON Project
- Product
- cJSON
- Classifications
- CWE-190
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 27, 2026CVE publishedPublication date reported by the CVE source.
- Jul 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=1.7.19
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
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Your stack
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