Vulnerability · Published Aug 11, 2026 · Assigned by VulnCheck

CVE-2026-29036cJSON 1.7.19 Wrong-Key Modification via JSON Pointer Escape Decoding

High 7.5

In plain English

A high-severity security flaw in cJSON from DaveGamble. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.4%top 61.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	cjson	no fix listed	DEBIAN-CVE-2026-29036
Debian:13	cjson	no fix listed	DEBIAN-CVE-2026-29036
Debian:14	cjson	no fix listed	DEBIAN-CVE-2026-29036
Ubuntu:26.04:LTS	cjson	no fix listed	UBUNTU-CVE-2026-29036
Ubuntu:26.10	cjson	no fix listed	UBUNTU-CVE-2026-29036

Affected products (as reported)

Vendor	Product	Versions
DaveGamble	cJSON	1.5.0 – through 1.7.19

Weakness: CWE-706 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Product Repository product
https://www.vulncheck.com/advisories/cjson-wrong-key-modification-via-json-pointer-escape-decoding third-party-advisory