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Fencer Vulns
medium 5.9

CVE-2026-66822 json

.NET Information Disclosure Vulnerability

published 2026-10-13 26 d ago modified 2026-10-31 8 d ago also GHSA-wxxw-5cvc-53j7 , EUVD-2026-99277

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 56%
public exploits
0
none known

Summary

Insertion of sensitive information into sent data in .NET allows an unauthorized attacker to disclose information over a network.

Patch / fix

  • nuget Microsoft.NETCore.App.Runtime.linux-arm 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.linux-arm64 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.linux-musl-arm 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.linux-musl-arm64 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.linux-musl-x64 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.linux-x64 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.osx-arm64 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.osx-x64 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.win-arm64 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.win-x64 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • nuget Microsoft.NETCore.App.Runtime.win-x86 8.0.32, 9.0.21, 10.0.13, 11.0.0-rc.2
  • Microsoft .NET 10.0 runtime 10.0.13
  • Microsoft .NET 11.0 runtime 11.0.0-rc.2
  • Microsoft .NET 8.0 runtime 8.0.32
  • Microsoft .NET 9.0 runtime 9.0.21
  • Microsoft Microsoft Visual Studio 2022 version 17.14 17.14.42
  • Microsoft Microsoft Visual Studio 2026 version 18.10 18.10.4
  • dotnet8 Ubuntu 22.04 LTS 8.0.132-8.0.32-0ubuntu1~22.04.1
  • dotnet8 Ubuntu 24.04 LTS 8.0.132-8.0.32-0ubuntu1~24.04.1
  • dotnet10 Ubuntu 24.04 LTS 10.0.113-10.0.13-0ubuntu1~24.04.1
  • dotnet10 Ubuntu 26.10 10.0.113-10.0.13-0ubuntu1~26.10.1
  • dotnet10 Ubuntu 26.04 LTS 10.0.113-10.0.13-0ubuntu1~26.04.1
  • dotnet11 Ubuntu 26.10 11.0.100-11.0.0~rc2-0ubuntu1~26.10.1

ubuntu advisories UBUNTU-CVE-2026-66822

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dotnet8.0 hummingbird 1 8.0.132-0.1.hum1
  • dotnet-sdk-8.0 hummingbird 1 8.0.132-0.1.hum1
  • dotnet-hostfxr-8.0 hummingbird 1 8.0.32-0.1.hum1
  • dotnet-runtime-8.0 hummingbird 1 8.0.32-0.1.hum1
  • dotnet-sdk-dbg-8.0 hummingbird 1 8.0.132-0.1.hum1
  • dotnet-templates-8.0 hummingbird 1 8.0.132-0.1.hum1
  • aspnetcore-runtime-8.0 hummingbird 1 8.0.32-0.1.hum1
  • dotnet-runtime-dbg-8.0 hummingbird 1 8.0.32-0.1.hum1

red hat advisories RHSA-2026:84693RHSA-2026:84491RHSA-2026:84424

  • dotnet-sdk-8.0 AlmaLinux 8 8.0.132-2.el8_10
  • dotnet-hostfxr-8.0 AlmaLinux 8 8.0.32-2.el8_10
  • dotnet-runtime-8.0 AlmaLinux 8 8.0.32-2.el8_10
  • dotnet-sdk-dbg-8.0 AlmaLinux 8 8.0.132-2.el8_10
  • dotnet-templates-8.0 AlmaLinux 8 8.0.132-2.el8_10
  • aspnetcore-runtime-8.0 AlmaLinux 8 8.0.32-2.el8_10
  • dotnet-runtime-dbg-8.0 AlmaLinux 8 8.0.32-2.el8_10
  • dotnet-apphost-pack-8.0 AlmaLinux 8 8.0.32-2.el8_10

almalinux advisories ALSA-2026:86594ALSA-2026:86168ALSA-2026:86169ALSA-2026:86170ALSA-2026:86171ALSA-2026:86172

  • dotnet8.0 Rocky Linux 10 8.0.132-1.el10_2
  • dotnet9.0 Rocky Linux 10 9.0.122-1.el10_2
  • dotnet10.0 Rocky Linux 10 10.0.113-1.el10_2
  • dotnet8.0 Rocky Linux 9 8.0.132-1.el9_8
  • dotnet9.0 Rocky Linux 9 9.0.122-1.el9_8
  • dotnet10.0 Rocky Linux 9 10.0.113-1.el9_8
  • dotnet9.0 Rocky Linux 8 9.0.122-1.el8_10
  • dotnet10.0 Rocky Linux 8 10.0.113-1.el8_10

rocky linux advisories RLSA-2026:86168RLSA-2026:86172RLSA-2026:86195RLSA-2026:86169RLSA-2026:86171RLSA-2026:86193

  • dotnet8-runtime Alpine 3.24, Alpine 3.23, Alpine 3.22 8.0.32-r0
  • dotnet9-runtime Alpine 3.24, Alpine 3.23, Alpine 3.22 9.0.21-r0
  • dotnet10-runtime Alpine 3.24, Alpine 3.23 10.0.13-r0

alpine advisories ALPINE-CVE-2026-66822

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-66822 updated cvss 5.9

dotnet10.0: dotnet8.0: dotnet9.0: dotnet: .NET Information Disclosure Vulnerability

  • Red Hat CodeReady Linux Builder EUS (v.9.6) dotnet-sdk-8.0-source-built-artifacts 8.0.132-1.el9_6, dotnet-sdk-9.0-source-built-artifacts 9.0.122-1.el9_6
    fixed: vendor fix RHSA-2026:88422
  • Red Hat Enterprise Linux AppStream (v. 8) dotnet 10.0.113-1.el8_10, dotnet8.0 8.0.132-2.el8_10, dotnet9.0 9.0.122-1.el8_10, dotnet10.0 10.0.113-1.el8_10, dotnet-sdk-8.0 8.0.132-2.el8_10, dotnet-sdk-9.0 9.0.122-1.el8_10, +34 more
    fixed: vendor fix RHSA-2026:86192
  • Red Hat Enterprise Linux AppStream (v. 9) dotnet8.0 8.0.132-1.el9_8, dotnet9.0 9.0.122-1.el9_8, dotnet-host 10.0.13-1.el9_8, dotnet10.0 10.0.113-1.el9_8, dotnet-sdk-8.0 8.0.132-1.el9_8, dotnet-sdk-9.0 9.0.122-1.el9_8, +34 more
    fixed: vendor fix RHSA-2026:86193
  • Red Hat Enterprise Linux AppStream (v. 10) dotnet8.0 8.0.132-1.el10_2, dotnet9.0 9.0.122-1.el10_2, dotnet-host 10.0.13-1.el10_2, dotnet10.0 10.0.113-1.el10_2, dotnet-sdk-8.0 8.0.132-1.el10_2, dotnet-sdk-9.0 9.0.122-1.el10_2, +34 more
    fixed: vendor fix RHSA-2026:86195
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) dotnet8.0 8.0.132-1.el9_4, dotnet-host 8.0.32-1.el9_4, dotnet-sdk-8.0 8.0.132-1.el9_4, dotnet-hostfxr-8.0 8.0.32-1.el9_4, dotnet-runtime-8.0 8.0.32-1.el9_4, dotnet-sdk-dbg-8.0 8.0.132-1.el9_4, +8 more
    fixed: vendor fix RHSA-2026:88425
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) dotnet8.0 8.0.132-1.el10_0, dotnet9.0 9.0.122-1.el10_0, dotnet-host 9.0.21-1.el10_0, dotnet-sdk-8.0 8.0.132-1.el10_0, dotnet-sdk-9.0 9.0.122-1.el10_0, dotnet-hostfxr-8.0 8.0.32-1.el10_0, +21 more
    fixed: vendor fix RHSA-2026:88474
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) dotnet8.0 8.0.132-1.el9_6, dotnet9.0 9.0.122-1.el9_6, dotnet-host 9.0.21-1.el9_6, dotnet-sdk-8.0 8.0.132-1.el9_6, dotnet-sdk-9.0 9.0.122-1.el9_6, dotnet-hostfxr-8.0 8.0.32-1.el9_6, +21 more
    fixed: vendor fix RHSA-2026:88422
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) dotnet-sdk-8.0-source-built-artifacts 8.0.132-1.el9_8, dotnet-sdk-9.0-source-built-artifacts 9.0.122-1.el9_8, dotnet-sdk-10.0-source-built-artifacts 10.0.113-1.el9_8
    fixed: vendor fix RHSA-2026:86193
show 5 more
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) dotnet-sdk-8.0-source-built-artifacts 8.0.132-1.el10_2, dotnet-sdk-9.0-source-built-artifacts 9.0.122-1.el10_2, dotnet-sdk-10.0-source-built-artifacts 10.0.113-1.el10_2
    fixed: vendor fix RHSA-2026:86195
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) dotnet-sdk-8.0-source-built-artifacts 8.0.132-1.el10_0, dotnet-sdk-9.0-source-built-artifacts 9.0.122-1.el10_0
    fixed: vendor fix RHSA-2026:88474
  • Red Hat Enterprise Linux CRB (v. 8) dotnet-sdk-8.0-source-built-artifacts 8.0.132-2.el8_10, dotnet-sdk-9.0-source-built-artifacts 9.0.122-1.el8_10, dotnet-sdk-10.0-source-built-artifacts 10.0.113-1.el8_10
    fixed: vendor fix RHSA-2026:86192
  • Red Hat Hardened Images dotnet10.0 10.0.113-1.hum1, dotnet8.0 8.0.132-0.1.hum1, dotnet9.0 9.0.122-0.1.hum1, dotnet-sdk-10.0 10.0.113-1.hum1, dotnet-sdk-8.0 8.0.132-0.1.hum1, dotnet-sdk-9.0 9.0.122-0.1.hum1, +20 more
    fixed: vendor fix RHSA-2026:84424
  • Red Hat Hardened Images dotnet-host 10.0.13-1.hum1, dotnet-hostfxr-10.0 10.0.13-1.hum1, dotnet-hostfxr-8.0 8.0.32-0.1.hum1, dotnet-runtime-10.0 10.0.13-1.hum1, dotnet-runtime-8.0 8.0.32-0.1.hum1, aspnetcore-runtime-10.0 10.0.13-1.hum1, +11 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
26 d ago

Exploit prediction

0.78% chance of exploitation in the next 30 days, higher than 56% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
nuget Microsoft.NETCore.App.Runtime.linux-arm
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.linux-arm64
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.linux-musl-arm
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.linux-musl-arm64
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.linux-musl-x64
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.linux-x64
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.osx-arm64
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.osx-x64
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.win-arm64
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.win-x64
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32
nuget Microsoft.NETCore.App.Runtime.win-x86
>=9.0.0, <9.0.21
>=11.0.0-preview.1, <11.0.0-rc.2
>=10.0.0, <10.0.13
>=8.0.0, <8.0.32
9.0.21
11.0.0-rc.2
10.0.13
8.0.32

Affected products

  • Microsoft .NET 10.0 runtime
  • Microsoft .NET 11.0 runtime
  • Microsoft .NET 8.0 runtime
  • Microsoft .NET 9.0 runtime
  • Microsoft Microsoft Visual Studio 2022 version 17.14
  • Microsoft Microsoft Visual Studio 2026 version 18.10

Classification

Weakness
  • CWE-201 Insertion of Sensitive Information Into Sent Data

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.