Vulnerability · Published Jul 29, 2026 · Assigned by VulnCheck
CVE-2026-67217cJSON JSON Patch Non-Atomic Application Destroys Data Before Validation
Medium 5.3
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 0.4% (higher than 38% of all known vulnerabilities).
Official description
cJSON through 1.7.19 applies RFC 6902 JSON Patch operations non-atomically in apply_patch() in cJSON_Utils.c. For a replace operation that is missing its value member, or a move operation whose destination path cannot be resolved, the existing target member is detached and deleted before the operation is fully validated, so the target document is mutated while cJSONUtils_ApplyPatches() or cJSONUtils_ApplyPatchesCaseSensitive() returns a failure status. An attacker who can supply the patch document can destroy addressable members of the target document even though the API reports that the patch failed, defeating the all-or-nothing behavior callers rely on to reject bad patches.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | cjson | no fix listed | DEBIAN-CVE-2026-67217 |
| Debian:13 | cjson | no fix listed | DEBIAN-CVE-2026-67217 |
| Debian:14 | cjson | no fix listed | DEBIAN-CVE-2026-67217 |
| Ubuntu:26.04:LTS | cjson | no fix listed | UBUNTU-CVE-2026-67217 |
| Ubuntu:26.10 | cjson | no fix listed | UBUNTU-CVE-2026-67217 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| DaveGamble | cJSON | 0 – through 1.7.19 |
Weakness: CWE-696 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N