Vulnerability in Microsoft System.Security.Cryptography.Xml (CVE-2026-96960)
Summary
Vulnerability in Microsoft System.Security.Cryptography.Xml (CVE-2026-96960). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 9.0.21 or later.
Original description
The description as published by the source.
Executive summary
Microsoft is releasing this security advisory to provide information about a vulnerability in System.Security.Cryptography.Xml; System.Private.Xml. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
Signed XML fixes add input-depth and operation-count limits, prohibit DTD processing by default, validate entity references, bound encrypted-data candidate processing, and cap attributes and namespaces used by C14N transforms.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/490
CVSS Details
-
Version: 3.1
-
Severity: High
-
Score: 7.5
-
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H -
Weakness: CWE-405 (Asymmetric Resource Consumption (Amplification))
Affected Platforms
- Platforms: Windows, Linux, macOS
- Architectures: All
Affected Packages
The vulnerability affects Microsoft .NET projects that use an affected package version listed below.
| Package name | Affected version | Patched version |
|---|---|---|
| System.Security.Cryptography.Xml | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| System.Security.Cryptography.Xml | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| [System.Security.Cryptography.Xml](https://www.nuget.org/p… |
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-96960 has been found in Microsoft System.Security.Cryptography.Xml.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade Microsoft System.Security.Cryptography.Xml to 9.0.21 or later.
If unsure, ask your IT team or search "Microsoft System.Security.Cryptography.Xml CVE-2026-96960" on the vendor's site.
CVE-2026-96960 (Microsoft System.Security.Cryptography.Xml) — CWE-405 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 9.0.21 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-405) exists in Microsoft System.Security.Cryptography.Xml.
Check the vendor advisory for the affected versions of Microsoft System.Security.Cryptography.Xml.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 9.0.21.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'System.Security.Cryptography.Xml' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'System.Security.Cryptography.Xml' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
System.Security.Cryptography.Xmlを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Microsoft System.Security.Cryptography.Xml to 9.0.21ステージング環境で 9.0.21 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- patch secure@microsoft.com
- web github.com
- web github.com
- web github.com