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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2025-3857

HIGH · 7.5 CVSS v3.1 Published 2025-04-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
When reading binary Ion data through Amazon.IonDotnet using the RawBinaryReader class, Amazon.IonDotnet does not check the number of bytes read from the underlying stream while deserializing the binary format. If the Ion data is malformed or truncated, this triggers an infinite loop condition that could potentially result in a denial of service. Users should upgrade to Amazon.IonDotnet version 1.3.1 and ensure any forked or derivative code is patched to incorporate the new fixes.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Amazon.IonDotnet library's RawBinaryReader class fails to validate byte counts when deserializing binary Ion data from streams. When malformed or truncated Ion data is processed, the lack of byte-read validation creates an infinite loop condition, causing denial of service through CPU exhaustion.

MitigationUpgrade Amazon.IonDotnet to version 1.3.1 or later, and audit any forked or derivative implementations for the same vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate Amazon.IonDotnet in your dependencies
    Search project files (.csproj, packages.config, .nuspec) and NuGet restore outputs for 'Amazon.IonDotnet' or 'IonDotnet' package references
    Affected if The package is present in your dependencies
  2. Identify the installed version
    Check the version attribute in the PackageReference, packages.config entry, or run 'dotnet list package --include-transitive' to see resolved versions
    Affected if Version is lower than 1.3.1 (e.g., 1.3.0, 1.2.x, 1.1.x, or any pre-1.3.1 release)
  3. Find RawBinaryReader usage in code
    Search source code for 'RawBinaryReader' class instantiation or method calls (e.g., 'new RawBinaryReader', 'IonReaderFactory.ReadBinaryReader')
    Affected if Code directly or indirectly invokes RawBinaryReader to parse binary Ion data
  4. Identify stream input sources
    Review code paths where RawBinaryReader reads from streams, especially from network sources, file uploads, or any untrusted input
    Affected if RawBinaryReader processes Ion data from streams that could be malformed, truncated, or attacker-controlled

You are affected if Amazon.IonDotnet version is below 1.3.1 AND your code uses RawBinaryReader to deserialize binary Ion data from streams, particularly untrusted or potentially truncated input.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Amazon.IonDotnet to version 1.3.1 or later, and audit any forked or derivative implementations for the same vulnerability.

Recommended fix High confidence

Amazon.IonDotnet version 1.3.1

  1. Identify the current version of Amazon.IonDotnet being used in your project by examining your NuGet package references or dependency files
  2. Check for any forked or derivative code that may be based on Amazon.IonDotnet and ensure those are also identified for patching
  3. Update the Amazon.IonDotnet package to version 1.3.1 via your NuGet package manager (e.g., dotnet add package Amazon.IonDotnet --version 1.3.1 or via Visual Studio NuGet UI)
  4. Rebuild your project to ensure the new version is correctly integrated
  5. If using forked or derivative code, manually apply the byte-reading validation fix to the RawBinaryReader class to check bytes read from the underlying stream during deserialization
  6. Test the application with the updated library to confirm the infinite loop vulnerability is mitigated

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-3857 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data