CVE-2026-67217 cJSON JSON Patch Non-Atomic Application Destroys Data Before Validation

Medium 6.9 Published 29 Jul 2026 Updated 29 Jul 2026

Attackers can destroy data in JSON documents by supplying malformed patches that fail validation after mutation, affecting applications using cJSON.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-67217?

CVE-2026-67217 is a medium-severity vulnerability in DaveGamble cJSON, published on 29 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

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.

Weakness: CWE-696

Which versions are affected by CVE-2026-67217?

It affects 1 product.

Products include Davegamble Cjson.

How do I fix CVE-2026-67217?

No fix has been published for CVE-2026-67217 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-67217 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-67217 exists.

Sources

Also known as DEBIAN-CVE-2026-67217, GHSA-pr46-97qf-f32c, UBUNTU-CVE-2026-67217.