CVE-2026-67216
cJSON cJSON_Compare Exponential Complexity Denial of Service
HIGH 8.2EPSS 0.6%
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
- DaveGamble · cJSON
- CVSS v4.0 VULNCHECK
- 8.2 HIGH
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS v3.1 NVD
- 7.5 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS v3.1 VULNCHECK
- 5.9 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS
- 0.65% chance of exploitation in the next 30 days, 50th percentile
- Published
- 2026-07-29
- Updated
- 2026-07-30
Proof-of-concept exploits (1)
Security advisories
- https://www.vulncheck.com/advisories/cjson-cjson-compare-exponential-complexity-denial-of…
- DaveGamble/cJSON/blob/v1.7.19/cJSON.c#L3057-L3180