# Microsoft Security Advisory CVE-2026-50526 – .NET Tampering Vulnerability

Advisory record · `GHSA-55jh-fwmh-39m4`

- **Identifiers:** `GHSA-55jh-fwmh-39m4` · `BIT-dotnet-2026-50526` · `BIT-dotnet-sdk-2026-50526` · `CVE-2026-50526`
- **State:** Confirmed
- **Severity:** CVSS 7.0 High
- **Critical:** No
- **Weakness (CWE):** [CWE-59](https://cwe.mitre.org/data/definitions/59.html) · [CWE-345](https://cwe.mitre.org/data/definitions/345.html)
- **Tags:** [Path traversal](https://agentprime.io/advisories/tag/path-traversal.md) · [CWE-345](https://agentprime.io/advisories/tag/cwe-345.md)
- **Published:** 21 Jul 2026
- **Updated:** 27 Jul 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 21 Jul 2026, 16:14 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `Microsoft.NET.Build.Containers` (NuGet): affected `>=10.0.0, <10.0.10 || >=9.0.0, <9.0.18 || >=8.0.0, <8.0.29`; fixed in `10.0.10`, `9.0.18`, `8.0.29`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 7.0 High, CVSS 3.1: `CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`, from CNA (microsoft)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0022, the 13th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 14 Jul 2026, 19:29 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-50526)
- 31 Oct 2026, 15:22 UTC: First seen by agentprime
- 31 Oct 2026, 15:22 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-55jh-fwmh-39m4)

## Sources

- [GitHub Advisory Database: GHSA-55jh-fwmh-39m4](https://github.com/advisories/GHSA-55jh-fwmh-39m4)
- [OSV: GHSA-55jh-fwmh-39m4](https://osv.dev/vulnerability/GHSA-55jh-fwmh-39m4)
- <https://github.com/dotnet/sdk/security/advisories/GHSA-55jh-fwmh-39m4>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-50526>
- <https://github.com/dotnet/announcements/issues/415>
- <https://github.com/dotnet/sdk/issues/55274>
- <https://github.com/dotnet/sdk>
- <https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50526>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-55jh-fwmh-39m4>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-55jh-fwmh-39m4/>. Everything for agents: <https://agentprime.io/llms.txt>.