Alibaba fastjson up to 1.2.83 input validation

Summaryinfo

A vulnerability was found in Alibaba fastjson up to 1.2.83. It has been declared as critical. Impacted is an unknown function. Executing a manipulation can lead to input validation. This vulnerability is handled as CVE-2026-16723. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability has been found in Alibaba fastjson up to 1.2.83 and classified as critical. This vulnerability affects some unknown processing. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

A remote code execution (RCE) vulnerability exists in fastjson 1.2.68 through 1.2.83. This vulnerability is exploitable under fastjson's stock default configuration — no AutoType enablement required, no classpath gadget required.

The advisory is available at github.com. This vulnerability was named CVE-2026-16723 since 07/23/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 07/23/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• Alibaba

Name

• fastjson

Version

• 1.2.0
• 1.2.1
• 1.2.2
• 1.2.3
• 1.2.4
• 1.2.5
• 1.2.6
• 1.2.7
• 1.2.8
• 1.2.9
• 1.2.10
• 1.2.11
• 1.2.12
• 1.2.13
• 1.2.14
• 1.2.15
• 1.2.16
• 1.2.17
• 1.2.18
• 1.2.19
• 1.2.20
• 1.2.21
• 1.2.22
• 1.2.23
• 1.2.24
• 1.2.25
• 1.2.26
• 1.2.27
• 1.2.28
• 1.2.29
• 1.2.30
• 1.2.31
• 1.2.32
• 1.2.33
• 1.2.34
• 1.2.35
• 1.2.36
• 1.2.37
• 1.2.38
• 1.2.39
• 1.2.40
• 1.2.41
• 1.2.42
• 1.2.43
• 1.2.44
• 1.2.45
• 1.2.46
• 1.2.47
• 1.2.48
• 1.2.49
• 1.2.50
• 1.2.51
• 1.2.52
• 1.2.53
• 1.2.54
• 1.2.55
• 1.2.56
• 1.2.57
• 1.2.58
• 1.2.59
• 1.2.60
• 1.2.61
• 1.2.62
• 1.2.63
• 1.2.64
• 1.2.65
• 1.2.66
• 1.2.67
• 1.2.68
• 1.2.69
• 1.2.70
• 1.2.71
• 1.2.72
• 1.2.73
• 1.2.74
• 1.2.75
• 1.2.76
• 1.2.77
• 1.2.78
• 1.2.79
• 1.2.80
• 1.2.81
• 1.2.82
• 1.2.83

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