Vulnerability · Published Jul 29, 2026 · Assigned by VulnCheck
CVE-2026-67216cJSON cJSON_Compare Exponential Complexity Denial of Service
Medium 5.9
In plain English
A medium-severity security flaw in cJSON from DaveGamble. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities).
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | cjson | no fix listed | DEBIAN-CVE-2026-67216 |
| Debian:13 | cjson | no fix listed | DEBIAN-CVE-2026-67216 |
| Debian:14 | cjson | no fix listed | DEBIAN-CVE-2026-67216 |
| Ubuntu:26.04:LTS | cjson | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:26.10 | cjson | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:26.04:LTS | iperf3 | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:26.10 | iperf3 | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:22.04:LTS | mapcache | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:24.04:LTS | mapcache | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:26.04:LTS | mapcache | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:26.10 | mapcache | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:26.04:LTS | sail-ocaml | no fix listed | UBUNTU-CVE-2026-67216 |
| Ubuntu:26.10 | sail-ocaml | no fix listed | UBUNTU-CVE-2026-67216 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| DaveGamble | cJSON | 0 – through 1.7.19 |
Weakness: CWE-407 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- Security vulnerabilities in the cJSON JSON parser (Joshua Rogers) exploit
- cJSON_Compare double-recursion object comparison (cJSON.c) technical-description
- VulnCheck Advisory: cJSON cJSON_Compare Exponential Complexity Denial of Service third-party-advisory