CVE-2026-67216Public exploitNetwork attack vector

Application hang via exponential object comparison

Published Jul 29, 2026 · Updated Jul 29, 2026

Algorithmic complexity in cJSON 1.7.19 and earlier allows remote attackers to hang applications through deeply nested JSON comparisons. cJSON_Compare() walks every shared object subtree twice, once in each direction, without a depth guard, so equal nested objects drive exponential CPU work. Exposure requires a host application to compare attacker-influenced JSON with a structurally matching document; parsing, validation, or serialization alone is unaffected.

CVSS severity8.2
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic complexity in cJSON 1.7.19 and earlier allows remote attackers to hang applications through deeply nested JSON comparisons. cJSON_Compare() walks every shared object subtree twice, once in each direction, without a depth guard, so equal nested objects drive exponential CPU work. Exposure requires a host application to compare attacker-influenced JSON with a structurally matching document; parsing, validation, or serialization alone is unaffected.

The record

CVE
CVE-2026-67216
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
cJSON Project
Product
cJSON
Classifications
CWE-407, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=1.7.19

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

cJSON Project · cJSONversion=0 <=1.7.19

Published CVSS scores

5.9VulnCheckCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.2VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-407Inefficient Algorithmic Complexity
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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