What’s Vulnerable › Vulnerabilities

CVE-2026-67216: cJSON cJSON_Compare Exponential Complexity Denial of Service

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-29 · updated 2026-10-23
• Weakness: CWE-407

Description

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.

Affected products

• DaveGamble cJSON: through 1.7.19

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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