CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
Percentile
69.8%
Newtonsoft.Json prior to version 13.0.1 is vulnerable to Insecure Defaults due to improper handling of expressions with high nesting level that lead to StackOverFlow exception or high CPU and RAM usage. Exploiting this vulnerability results in Denial Of Service (DoS).
The serialization and deserialization path have different properties regarding the issue.
Deserializing methods (like JsonConvert.DeserializeObject
) will process the input that results in burning the CPU, allocating memory, and consuming a thread of execution. Quite high nesting level (>10kk, or 9.5MB of {a:{a:{...
input) is needed to achieve the latency over 10 seconds, depending on the hardware.
Serializing methods (like JsonConvert.Serialize
or JObject.ToString
) will throw StackOverFlow exception with the nesting level of around 20k.
To mitigate the issue one either need to update Newtonsoft.Json to 13.0.1 or set MaxDepth
parameter in the JsonSerializerSettings
. This can be done globally with the following statement. After that the parsing of the nested input will fail fast with Newtonsoft.Json.JsonReaderException
:
JsonConvert.DefaultSettings = () => new JsonSerializerSettings { MaxDepth = 128 };
Repro code:
//Create a string representation of an highly nested object (JSON serialized)
int nRep = 25000;
string json = string.Concat(Enumerable.Repeat("{a:", nRep)) + "1" +
string.Concat(Enumerable.Repeat("}", nRep));
//Parse this object (leads to high CPU/RAM consumption)
var parsedJson = JsonConvert.DeserializeObject(json);
// Methods below all throw stack overflow with nRep around 20k and higher
// string a = parsedJson.ToString();
// string b = JsonConvert.SerializeObject(parsedJson);
The original statement about the problem only affecting IIS applications is misleading. Any application is affected, however the IIS has a behavior that stops restarting the instance after some time resulting in a harder-to-fix DoS.**
Vendor | Product | Version | CPE |
---|---|---|---|
* | newtonsoft.json | * | cpe:2.3:a:*:newtonsoft.json:*:*:*:*:*:*:*:* |
alephsecurity.com/2018/10/22/StackOverflowException/
alephsecurity.com/vulns/aleph-2018004
github.com/advisories/GHSA-5crp-9r3c-p9vr
github.com/JamesNK/Newtonsoft.Json/commit/7e77bbe1beccceac4fc7b174b53abfefac278b66
github.com/JamesNK/Newtonsoft.Json/issues/2457
github.com/JamesNK/Newtonsoft.Json/pull/2462
security.snyk.io/vuln/SNYK-DOTNET-NEWTONSOFTJSON-2774678