Medium exploit reference

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

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.

Published Jul 29, 2026 · Updated Oct 16, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: VulnCheck

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.4% (30-day exploitation probability)+5
Technical severity (medium)+3
CISA SSVC: exploitation "poc"+5
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.43%

ahead of 36% of scored CVEs · Oct 15, 2026

Affects

Davegamble

Cjson

CVSS base

5.3

Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Davegamble Cjson).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Davegamble	Cjson	≤ 1.7.19	Vulnerable	NIST National Vulnerability Database
Davegamble	Cjson	≤ 1.7.19	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
6.9	CVSS 4.0	Medium	—	—	disclosure@vulncheck.com via NIST National Vulnerability Database
6.9	CVSS 4.0	Medium	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP
5.3	CVSS 3.1	Medium	3.9	1.4	disclosure@vulncheck.com via NIST National Vulnerability Database
5.3	CVSS 3.1	Medium	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N (score shown at the top: disclosure@vulncheck.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-696

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · davegamble/cjson
Oct 16, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 16, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
Fix documented
Oct 15, 2026 · NIST National Vulnerability Database
CVSS changed · 5.3
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Jul 29, 2026 · VulnCheck

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

3 on the record

github.com/DaveGamble/cJSON/blob/v1.7.19/cJSON_Utils.c
Patch, technical-description, NIST National Vulnerability Database
www.vulncheck.com/advisories/cjson-json-patch-non-atomic-application-destroys-data-befo
Third Party Advisory, third-party-advisory, NIST National Vulnerability Database
joshua.hu/cjson-json-parser-cve-vulnerabilities
Exploit, Press/Media Coverage, Third Party Advisory, exploit, NIST National Vulnerability Database

Elsewhere on this site

Davegamble
every CVE for this vendor

CWE-696
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-87933 DaveGamble cJSON cJSON_Utils.c cJSONUtils_MergePatch use after free Sep 9, 2026
High CVE-2026-29036 cJSON 1.7.19 Wrong-Key Modification via JSON Pointer Escape Decoding Aug 11, 2026
High CVE-2026-67215 cJSON JSON Patch copy/add Uncontrolled Recursion Stack Exhaustion Jul 29, 2026
High CVE-2026-67216 cJSON cJSON_Compare Exponential Complexity Denial of Service Jul 29, 2026
High CVE-2026-16554 Integer Overflow Leading to Heap Buffer Overflow in cJSON Jul 27, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-67217 is "cJSON JSON Patch Non-Atomic Application Destroys Data Before Validation", rated Medium. It affects Cjson (Davegamble); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.43% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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