CVE-2026-29036

cJSON 1.7.19 Wrong-Key Modification via JSON Pointer Escape Decoding

Assigner: VulnCheck
Reserved: 03.03.2026 Published: 11.08.2026 Updated: 11.08.2026

cJSON versions 1.5.0 through 1.7.19 contain an incorrectly-resolved name or reference vulnerability in the decode_pointer_inplace() function within cJSON_Utils.c that allows unauthenticated attackers to cause JSON Patch operations to target wrong object keys by supplying crafted JSON Pointer escape sequences (~0 or ~1) in patch paths. Attackers can submit malicious RFC 6902 JSON Patch input to applications using cJSONUtils_ApplyPatches() or cJSONUtils_ApplyPatchesCaseSensitive() to silently corrupt data or delete unintended keys, potentially bypassing authorization controls in applications that rely on JSON Patch for access-controlled data modification.

Metrics

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS Score: 8.7

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	None	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

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

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	High
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	DaveGamble
Product	cJSON
Versions	Default: affected affected from 1.5.0 to 1.7.19 (incl.)

Vendor

DaveGamble

Product

cJSON

Versions

Default: affected

affected from 1.5.0 to 1.7.19 (incl.)

Credits

Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc. finder

References

Problem Types