.Net: Bump Snappier to 1.3.1 to fix NU1903 high-severity vulnerability (GHSA-pggp-6c3x-2xmx)

[Copilot]

Motivation and Context

MongoDB.Driver 3.5.2 transitively introduces Snappier 1.0.0, which carries a high-severity vulnerability (GHSA-pggp-6c3x-2xmx): infinite loop during SnappyStream decompression of malformed framed input. All Snappier versions ≤ 1.3.0 are affected; 1.3.1 is the first patched release. This was blocking the merge queue via NU1903.

Description

• dotnet/Directory.Packages.props — Add PackageVersion entry pinning Snappier to 1.3.1.
• dotnet/src/VectorData/MongoDB/MongoDB.csproj — Add explicit PackageReference for Snappier (versionless, resolved via CPM) so NuGet treats it as a direct dependency at 1.3.1, overriding the transitive 1.0.0 from MongoDB.Driver.
• dotnet/src/VectorData/CosmosMongoDB/CosmosMongoDB.csproj — Same override for the CosmosMongoDB connector.

In NuGet's resolution algorithm, a direct reference at depth 1 wins over a transitive reference at depth 2, so this cleanly forces 1.3.1 without changing the MongoDB.Driver pin itself.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

Original prompt

Please investigate a solution to snappier vulnerability fix (update version) and propose a PR with the bump, ideally following the first immediate a non breaking version bump

**Chronological Review:** 1. User asked to analyze PR #13431 (Gemini multimodal tool results in microsoft/semantic-kernel) for gaps 2. Initial analysis identified ~11 gaps with broad scope including OpenAI Assistants, AzureAI, Responses API, MistralAI 3. User invoked ouroboros skill, asked to reassess scoping to Google package only 4. Reassessment: Google connector bypasses FunctionCallsProcessor; only validated regression is OpenAI Responses API 5. User invoked ouroboros to seed the observation; created seed file `pr-13431-followup.seed.yaml` 6. User asked to execute seed + identify pipeline error 7. Implemented 5 file changes; identified pipeline error CS8602 in GeminiRequestTests.cs:809 8. All builds/tests passed; user asked about string→object impact in plan mode 9. Investigation revealed `FunctionCallsProcessor` is `internal sealed`, source-distributed, so blast radius small 10. User confirmed all implemented; ran CI-parity dotnet format via WSL2+Docker (all pass) 11. User asked to commit and push - committed `de08bce99` and pushed to Cozmopolit fork 12. User asked to check PR comments - found 2 Copilot bot review comments 13. User said: add OpenAI test (item 1), reply out-of-scope (item 2) 14. Added OpenAI ChatCompletion test, committed `e9f27d21a`, pushed, replied to both bot comments 15. User asked PR number (13431) 16. User invoked /auto pr_task - PR was green, no action needed 17. User said merge queue failed, asked to investigate 18. Investigation found: NU1903 Snappier 1.0.0 vulnerability blocking merge queue; not caused by our PR 19. **Most recent: User asked "Do we have a fix in main for this already?"** 20. **Investigation confirmed: NO fix in main** - origin/main HEAD `1a5065e5c` unchanged, `MongoDB.Driver 3.5.2` still pinned, no Snappier override, no PRs/issues for Snappier or NU1903 in the repo recently 21. **Offered to open a small fix PR pinning Snappier to a patched version**

Intent Mapping:

• User wants PR .Net: feat(connectors): Support ImageContent in tool/function results #13431 fully landed
• User wants to understand whether merge queue failure is in scope
• User now considering whether to fix the Snappier vulnerability separately

Technical Inventory:

• .NET 10.0, semantic-kernel repo
• WSL2 + Docker (mcr.microsoft.com/dotnet/sdk:10.0) for CI parity
• gh CLI for PR/CI operations
• Git remotes: origin=microsoft, roger=rogerbarreto fork, cozmopolit=Cozmopolit fork (added)
• Branch: fix/multimodal-tool-results
• PR head fork: Cozmopolit, maintainerCanModify=true

Code Archaeology:
Files changed in commits de08bce99 + e9f27d21a:

• dotnet/src/Agents/OpenAI/Internal/ResponseThreadActions.cs — added GetFunctionResultAsString helper
• dotnet/src/Agents/UnitTests/OpenAI/Internal/ResponseThreadActionsTests.cs — new (3 tests)
• dotnet/src/Connectors/Connectors.Google/Core/Gemini/Models/GeminiRequest.cs — extracted s_imageFunctionResponseEnvelope
• dotnet/src/Connectors/Connectors.Google.UnitTests/Core/Gemini/GeminiRequestTests.cs — CS8602 fix
• dotnet/src/InternalUtilities/connectors/AI/FunctionCalling/FunctionCallsProcessor.cs — XML-doc tightening
• dotnet/src/Connectors/Connectors.OpenAI.UnitTests/Services/OpenAIChatCompletionServiceTests.cs — added ItSendsImageContentNotSupportedErrorWhenToolResultIsImageContentAsync

Identified vulnerable package: MongoDB.Driver 3.5.2 in dotnet/Directory.Packages.props:173 brings in transitive Snappier 1.0.0

Progress Assessment:

• ✅ All planned implementation completed
• ✅ Both bot review comments replied to
• ✅ All 7 todos done
• ⚠️ PR cannot merge due to environmental Snappier vulnerability (not our PR's fault)
• 🔲 User considering whether to open a separate Snappier fix PR

Context Validation:

• PR state: OPEN, MERGEABLE, CLEAN, APPROVED (markwallace-microsoft)
• HEAD SHA: e9f27d21a85a8b97ee5f29619b23b82a03e313ff
• All required CI checks pass on PR head
• Merge queue attempt failed at 2026-05-07T10:01:31, removed by github-merge-queue[bot] at 10:08:05
• Failed merge_group run: 25489152862

Recent Commands Analysis:
Most recent two tool batches:

1. git fetch origin main; git log origin/main --since="2026-05-06T15:00:00Z" --oneline → only 1a5065e5c (yesterday's commit)
2. git show origin/main:dotnet/Directory.Packages.props | grep Snappier|MongoDB.Driver → only MongoDB.Driver 3.5.2, no Snappier override
3. gh search prs/issues --state all "Snappier" → command failed (invalid all state)
4. gh api search/issues?q=Snappier+repo:microsoft/semantic-kernel → empty results
5. gh api search/issues?q=NU1903+repo:microsoft/semantic-kernel → 3 historical results from 2024, all unrelated

Final response: confirmed NO fix in main, offered to open a small fix PR pinning Snappier.

1. Conversation Overview: - Primary Objectives: - Analyze SK PR #13431 (G...

Created from Copilot CLI via the copilot delegate command.

[github-actions]

Automated Code Review

Reviewers: 4 | Confidence: 94% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Design Approach

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Automated review by rogerbarreto's agents

[Copilot]

Pull request overview

Pins the Snappier dependency to a patched version to address NU1903 / GHSA-pggp-6c3x-2xmx introduced transitively via MongoDB.Driver, ensuring affected VectorData MongoDB connectors restore a safe version without changing the MongoDB.Driver pin.

Changes:

• Add a CPM PackageVersion entry for Snappier 1.3.1.
• Add direct (versionless, CPM-resolved) PackageReference entries to Snappier in the MongoDB and CosmosMongoDB VectorData connector projects to override the vulnerable transitive version.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
dotnet/Directory.Packages.props	Central package version pin for Snappier 1.3.1.
dotnet/src/VectorData/MongoDB/MongoDB.csproj	Adds direct Snappier reference so NuGet resolves the patched version for this connector.
dotnet/src/VectorData/CosmosMongoDB/CosmosMongoDB.csproj	Adds direct Snappier reference so NuGet resolves the patched version for this connector.

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