CVE-2026-67216

cJSON through 1.7.19 contains an inefficient algorithmic complexity flaw in cJSON_Compare(). When comparing objects, the function recurses into each shared subtree twice, once in each direction, with no depth guard, making the running time exponential in nesting depth. A small, deeply nested document of a few hundred bytes (depth around 40) compared for equality consumes hours of CPU, and the cost roughly doubles with each additional level of nesting. An application that calls cJSON_Compare() on attacker-influenced JSON that is structurally equal to a reference document is exposed to a denial-of-service condition.

CVSS 4.0

8.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.6% chance of exploitation in the next 30 days; higher than 50% of CVEs (scores of 2026-10-25)

CWE

CWE-407

Published

2026-07-29

Modified

2026-10-23

Record from

the NVD, synced 2026-10-24

Affected

• davegamble:cjson

References

• https://github.com/DaveGamble/cJSON/blob/v1.7.19/cJSON.c#L3057-L3180
• https://joshua.hu/cjson-json-parser-cve-vulnerabilities
• https://www.vulncheck.com/advisories/cjson-cjson-compare-exponential-complexity-denial-of-service

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