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.NET Denial of Service Vulnerability

5.3MediumCNA
Exploited
No known exploitation
Fix
Fixed in 11.0.0
Who is exposed
Not reported

Do first: Upgrade to a fixed version: 11.0.0.

Published
Last modified
Reference
Last checked
32/100 · provisional
None on Exploit-DB, Metasploit or GitHub

Summary

Inefficient algorithmic complexity in .NET allows an unauthorized attacker to deny service over a network.

cve.now Index

32Pcve.now Index 32 of 100 · methodology v3 · provisional
  • Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
  • Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Unknown: No advisory context yet
  • Reach10/20Affects NuGet packages
  • Severity5.3/10CVSS 5.3
  • No patch0/5No signal

What would change the score

  • Would score about 77 if added to CISA KEV
  • Would score about 72 if CISA's SSVC rates exploitation active
  • Would score about 37 if advisories confirm default setups are exposed

What to do

  • Upgrade to a fixed version: 11.0.0.

Check your systems with an agent

Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.

Check whether my systems are affected by CVE-2026-120796 (.NET Denial of Service Vulnerability), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-120796 (entry last updated 2026-11-10):
Affected:
- Microsoft .NET 11.0 installed on Linux: from 11.0.0-preview.1, fixed in 11.0.0
- Microsoft .NET 11.0 installed on Mac OS: from 11.0.0-preview.1, fixed in 11.0.0
- Microsoft .NET 11.0 installed on Windows: from 11.0.0-preview.1, fixed in 11.0.0
- Microsoft System.Text.Json: from NOT_YET_AVAILABLE, fixed in 11.0.0
- NuGet package Microsoft.NETCore.App.Runtime.linux-arm: from 11.0.0-preview.1.26104.118, fixed in 11.0.0
- NuGet package Microsoft.NETCore.App.Runtime.linux-arm64: from 11.0.0-preview.1.26104.118, fixed in 11.0.0
- NuGet package Microsoft.NETCore.App.Runtime.linux-musl-arm: from 11.0.0-preview.1.26104.118, fixed in 11.0.0
- NuGet package Microsoft.NETCore.App.Runtime.linux-musl-arm64: from 11.0.0-preview.1.26104.118, fixed in 11.0.0
- NuGet package Microsoft.NETCore.App.Runtime.linux-musl-x64: from 11.0.0-preview.1.26104.118, fixed in 11.0.0
- NuGet package Microsoft.NETCore.App.Runtime.linux-x64: from 11.0.0-preview.1.26104.118, fixed in 11.0.0
- and 6 more affected products, listed on https://cve.now/CVE-2026-120796
Fixed versions: 11.0.0.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-120796 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-120796 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Packages (NuGet): find every lockfile in each project and run check_stack from the cve.now MCP server on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies.
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-120796
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-120796
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-120796.

Timeline

  1. CVE published
  2. Record last updated
  3. First seen by cve.now

Affected versions

  • Microsoft .NET 11.0 installed on Linux

    From 11.0.0-preview.1 · fixed in 11.0.0

  • Microsoft .NET 11.0 installed on Mac OS

    From 11.0.0-preview.1 · fixed in 11.0.0

  • Microsoft .NET 11.0 installed on Windows

    From 11.0.0-preview.1 · fixed in 11.0.0

  • Microsoft System.Text.Json

    From NOT_YET_AVAILABLE · fixed in 11.0.0

  • From 11.0.0-preview.1.26104.118 · fixed in 11.0.0

    Fixed in 11.0.0 (released Nov 10, 2026, the day of disclosure).

    The latest release, 11.0.0, is not affected.

  • From 11.0.0-preview.1.26104.118 · fixed in 11.0.0

    Fixed in 11.0.0 (released Nov 10, 2026, the day of disclosure).

    The latest release, 11.0.0, is not affected.

  • From 11.0.0-preview.1.26104.118 · fixed in 11.0.0

    Fixed in 11.0.0 (released Nov 10, 2026, the day of disclosure).

    The latest release, 11.0.0, is not affected.

  • From 11.0.0-preview.1.26104.118 · fixed in 11.0.0

    Fixed in 11.0.0 (released Nov 10, 2026, the day of disclosure).

    The latest release, 11.0.0, is not affected.

Show all 16 packagesShow fewer packages

Evidence 3

Vendor advisory · 1

Establishes: Affected and fixed versions.

  1. Patch

CVE record · 2

Establishes: The identifier and description.

  1. Record
  2. Record

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-120796

Is CVE-2026-120796 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

Which versions are affected by CVE-2026-120796?

.NET 11.0 installed on Linux: from 11.0.0-preview.1 before 11.0.0. .NET 11.0 installed on Mac OS: from 11.0.0-preview.1 before 11.0.0. .NET 11.0 installed on Windows: from 11.0.0-preview.1 before 11.0.0. System.Text.Json: from NOT_YET_AVAILABLE before 11.0.0. Microsoft.NETCore.App.Runtime.linux-arm (NuGet): from 11.0.0-preview.1.26104.118 before 11.0.0. 11 more packages are listed on the page.Source: cve.now feed data

How do I fix CVE-2026-120796?

Upgrade to a fixed version: 11.0.0.Source: cve.now feed data