CVE-2026-67215

cJSON JSON Patch copy/add Uncontrolled Recursion Stack Exhaustion

cJSON through 1.7.19 is vulnerable to uncontrolled recursion leading to stack exhaustion when an untrusted RFC 6902 JSON Patch is applied via cJSONUtils_ApplyPatches() or cJSONUtils_ApplyPatchesCaseSensitive(). A patch containing add and copy operations grafts duplicated subtrees to amplify document depth beyond the parser's nesting limit: cJSON_Delete() recurses with no depth bound, and the cJSON_Duplicate() guard CJSON_CIRCULAR_LIMIT is set to 10000, ten times the parser's 1000-level nesting limit and high enough to overflow a default thread stack. An attacker who can supply the patch document can crash the process, resulting in denial of service.

Affected

DaveGamble · cJSON

CVSS v4.0 VULNCHECK

8.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/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 VULNCHECK

7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.70% chance of exploitation in the next 30 days, 52nd percentile

Published

2026-07-29

Proof-of-concept exploits (1)

• https://joshua.hu/cjson-json-parser-cve-vulnerabilities

Security advisories

• https://www.vulncheck.com/advisories/cjson-json-patch-copy-add-uncontrolled-recursion-sta…
• DaveGamble/cJSON/blob/v1.7.19/cJSON.c#L253-L261

References

• CVE Record
• NVD entry