{"id":"CVE-2026-116477","kind":"vulnerability","aliases":["CVE-2026-116477"],"related":[],"title":"a2a-dotnet: JSON-RPC parser error messages expose internal details to remote callers","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.","summary":"The A2A .NET SDK's JSON-RPC request processor returns error messages that reveal internal information when handling crafted requests. A remote attacker can read that information from the responses.","severity":"medium","cvss":5.3,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["a2a-dotnet","asp.net-core","dotnet","package","self-hosted"],"not_affected_if":["default-config"],"how_to_check":"- Check the installed `A2A` package version in the project's NuGet references (for example `dotnet list package`); versions up to `1.0.0-preview2` are affected.\n- Check whether the service hosts the A2A JSON-RPC endpoint via the ASP.NET Core integration in `src/A2A.AspNetCore/A2AJsonRpcProcessor.cs`.","fix":"- Upgrade the a2a-dotnet package to `1.0.0-preview3` or later, per the patch `ccbd12b6108a6a8f0fd5d8b4a9ece3c8a94ba1e4`.","status":"open","published_at":"2026-10-26T20:17:54+00:00","first_seen_at":"2026-10-26T20:50:17+00:00","triaged_at":"2026-10-26T20:51:53+00:00","updated_at":"2026-10-26T20:51:53+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-26T20:51:53Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade the a2a-dotnet package to `1.0.0-preview3` or later, per the patch `ccbd12b6108a6a8f0fd5d8b4a9ece3c8a94ba1e4`.","reach":"internet","title":"a2a-dotnet: JSON-RPC parser error messages expose internal details to remote callers","impact":"low","summary":"The A2A .NET SDK's JSON-RPC request processor returns error messages that reveal internal information when handling crafted requests. A remote attacker can read that information from the responses.","category":"package","nicknames":[],"who_cares":["a2a-dotnet","dotnet","asp.net-core","self-hosted"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Remote callers read internal details from error responses.","analyst_note":"","how_to_check":"- Check the installed `A2A` package version in the project's NuGet references (for example `dotnet list package`); versions up to `1.0.0-preview2` are affected.\n- Check whether the service hosts the A2A JSON-RPC endpoint via the ASP.NET Core integration in `src/A2A.AspNetCore/A2AJsonRpcProcessor.cs`.","needs_analyst":false,"not_affected_if":["default-config"],"who_is_affected":"Teams running an ASP.NET Core service that uses the a2a-dotnet SDK at `1.0.0-preview2` or earlier to expose an A2A JSON-RPC endpoint are exposed. Services that do not use the SDK, or that run a newer preview, can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000636,"input_tokens":3447,"output_tokens":583,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-116477':18A,21A '-2026':17A,20A '1.0.0':76C,113C 'a2a':2A,23B,33B,72C 'a2a-dotnet':1A,22B,71C 'a2ajsonrpcprocessor.processrequestasync':84C 'a2aproject':70C 'affect':130C 'asp.net':25B 'attack':55B,108C 'caller':15A 'ccbd12b6108a6a8f0fd5d8b4a9ece3c8a94ba1e4':127C 'compon':91C,131C 'core':26B 'craft':51B 'cve':16A,19A 'detail':12A 'detect':68C 'dotnet':3A,24B,27B,73C 'element':80C 'error':8A,43B,100C 'expos':10A 'exposur':98C 'file':87C 'function':83C 'handl':50B 'host':31B 'identifi':122C 'impact':79C 'inform':48B,59B,97C 'initi':106C 'intern':11A,47B 'issu':120C 'json':5A,38B 'json-rpc':4A,37B 'lead':95C 'manipul':94C 'messag':9A,44B,101C 'net':34B 'packag':28B 'parser':7A,92C 'patch':125C 'possibl':104C 'preview2':77C 'preview3':114C 'processor':41B 'read':57B 'recommend':133C 'remot':14A,54B,109C 'request':40B,52B 'resolv':118C 'respons':62B 'return':42B 'reveal':46B 'rpc':6A,39B 'sdk':35B 'secur':64C 'self':30B 'self-host':29B 'src/a2a.aspnetcore/a2ajsonrpcprocessor.cs':88C 'suffici':116C 'upgrad':110C,128C 'version':112C 'vulner':65C","nicknames":[],"mitigations":[],"who_affected":"Teams running an ASP.NET Core service that uses the a2a-dotnet SDK at `1.0.0-preview2` or earlier to expose an A2A JSON-RPC endpoint are exposed. Services that do not use the SDK, or that run a newer preview, can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-26T20:17:54+00:00","kev":null,"cvss_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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"cna@vuldb.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-116477","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-116477","severity":null,"published_at":"2026-10-26T20:17:54+00:00","modified_at":"2026-10-26T20:17:54+00:00","first_seen_at":"2026-10-26T20:50:17+00:00","fetched_at":"2026-10-26T20:50:17+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}