Vulnerabilities in pkg:nuget/Nerdbank.MessagePack

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Advisory Summary

GHSA-92vj-hp7m-gwcj is a MODERATE (CVSS 5.3) nerdbank.messagepack has inefficient cpu computation vulnerability (CWE-1176: Inefficient CPU Computation) affecting Nerdbank.MessagePack libraries in the NuGet ecosystem. The issue involves nerdbank.messagepack has inefficient cpu computation. Remediation is available by upgrading affected packages to version 1.2.4.

3 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:nuget/Nerdbank.MessagePack

3 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:nuget/Nerdbank.MessagePack. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-92vj-hp7m-gwcj - MODERATE Nerdbank.MessagePack has Inefficient CPU Computation
GHSA-qjvr-435c-5fjh - MODERATE Nerdbank.MessagePack has a memory amplification DoS in collection deserialization
GHSA-2cwq-pwfr-wcw3 CVE-2026-44375 HIGH Nerdbank.MessagePack: Attacker-controlled stackalloc in DateTime decoding causes process-terminating StackOverflowException

GHSA-92vj-hp7m-gwcj at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-92vj-hp7m-gwcj
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-1176: Inefficient CPU Computation
Affected Product Nerdbank.MessagePack
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability Low (A:L)

How to Fix GHSA-92vj-hp7m-gwcj

To remediate this vulnerability, upgrade all affected Nerdbank.MessagePack dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Nerdbank.MessagePack fixed: 1.2.4 
Upgrade Nerdbank.MessagePack to 1.2.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for Nerdbank.MessagePack

How to Check if You Are Affected

To determine whether your application is affected by GHSA-92vj-hp7m-gwcj, inspect your project dependencies for Nerdbank.MessagePack:

inspect dependencies for Nerdbank.MessagePack

Analyze the terminal output to locate any version of Nerdbank.MessagePack in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.2.4), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1176: Inefficient CPU Computation, where the product performs cpu computations using algorithms that are not as efficient as they could be for the needs of the developer, i.e., the computations can be optimized further. In Nerdbank.MessagePack, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Applications that call `OptionalConverters.WithExpandoObjectConverter` and deserialize untrusted data are open to a vulnerability by which an attacker can exploit a `O(n²)` algorithm to burn an inordinate amount of CPU effort by adding a great many properties to an `ExpandoObject`, whose `Add` method is implemented as an `O(n)` algorithm. ### Patches Update to a patched version. If a project's `ExpandoObject` data requires more than 128 properties, the default limit should be changed: ```cs this.Serializer = this.Serializer with { StartingContext = this.Serializer.StartingContext with { Security = this.Serializer.StartingContext.Security with { ExpandoObjectMaxPropertyCount = 256, // Set this to whatever limit is required by your application }, }, }; ``` ### Workarounds Avoid the non-default `WithExpandoObjectConverter` extension method when deserializing untrusted data. If deserializing untrusted data into an `ExpandoObject` is required, developers should write a custom converter for their project that limits the number of properties allowed before initializing the object.

GHSA-92vj-hp7m-gwcj Affected Nerdbank.MessagePack Versions

1 component(s)
Fixed Versions:
1.2.4
Product / Package Ecosystem Affected Versions Fixed Version
Nerdbank.MessagePack
nuget/Nerdbank.MessagePack
NuGet
< 1.2.4
1.2.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/AArnott/Nerdbank.MessagePack/security/advisories/GHSA-92vj-hp7m-gwcj
Security Fix Commit FIX COMMIT
https://github.com/AArnott/Nerdbank.MessagePack/commit/c5a239e4f20c38548de44c4dd2a782efd5e2547c
Nerdbank.MessagePack Source Repository REPOSITORY
https://github.com/AArnott/Nerdbank.MessagePack

Frequently Asked Questions

What is GHSA-92vj-hp7m-gwcj?
GHSA-92vj-hp7m-gwcj is a security vulnerability in Nerdbank.MessagePack involving Nerdbank.MessagePack has Inefficient CPU Computation under CWE-1176: Inefficient CPU Computation.
Which Nerdbank.MessagePack versions are affected?
Affected versions include releases prior to 1.2.4 across affected packages: Nerdbank.MessagePack.
What version fixes GHSA-92vj-hp7m-gwcj?
Upgrading to 1.2.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Nerdbank.MessagePack affected?
Yes, Nerdbank.MessagePack is affected in releases prior to 1.2.4. Upgrade your dependency to 1.2.4 or later.
What is the CVSS score of GHSA-92vj-hp7m-gwcj?
GHSA-92vj-hp7m-gwcj has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
What CWE is associated with GHSA-92vj-hp7m-gwcj?
GHSA-92vj-hp7m-gwcj is classified under CWE-1176: Inefficient CPU Computation (The product performs CPU computations using algorithms that are not as efficient as they could be for the needs of the developer, i.e., the computations can be optimized further.).
How can I check NuGet dependencies for GHSA-92vj-hp7m-gwcj?
Run the dependency tree command: 'inspect dependencies for Nerdbank.MessagePack'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-92vj-hp7m-gwcj",
  "modified" : "2026-05-29T20:02:59Z",
  "published" : "2026-05-29T20:02:59Z",
  "aliases" : [ ],
  "summary" : "Nerdbank.MessagePack has Inefficient CPU Computation",
  "details" : "### Impact\n\nApplications that call `OptionalConverters.WithExpandoObjectConverter` and deserialize untrusted data are open to a vulnerability by which an attacker can exploit a `O(n²)` algorithm to burn an inordinate amount of CPU effort by adding a great many properties to an `ExpandoObject`, whose `Add` method is implemented as an `O(n)` algorithm.\n\n### Patches\n\nUpdate to a patched version.\n\nIf a project's `ExpandoObject` data requires more than 128 properties, the default limit should be changed:\n\n```cs\nthis.Serializer = this.Serializer with\n{\n\tStartingContext = this.Serializer.StartingContext with\n\t{\n\t\tSecurity = this.Serializer.StartingContext.Security with\n\t\t{\n\t\t\tExpandoObjectMaxPropertyCount = 256, // Set this to whatever limit is required by your application\n\t\t},\n\t},\n};\n```\n\n### Workarounds\n\nAvoid the non-default `WithExpandoObjectConverter` extension method when deserializing untrusted data.\nIf deserializing untrusted data into an `ExpandoObject` is required, developers should write a custom converter for their project that limits the number of properties allowed before initializing the object.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Nerdbank.MessagePack"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.2.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/AArnott/Nerdbank.MessagePack/security/advisories/GHSA-92vj-hp7m-gwcj"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/AArnott/Nerdbank.MessagePack/commit/c5a239e4f20c38548de44c4dd2a782efd5e2547c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/AArnott/Nerdbank.MessagePack"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1176" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-29T20:02:59Z",
    "nvd_published_at" : null
  }
}