Missing Authentication in the local .NET backend of Progress Telerik Fiddler Everywhere

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-86158
StatePUBLISHED
AssignerProgressSoftware
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-29 07:16:35 UTC
Updated2026-09-30 16:19:21 UTC
DescriptionMissing authentication in the local .NET backend (Fiddler.WebUi) of Progress Software Fiddler Everywhere 8.0.2 allows a local unauthenticated attacker to mint OAuth tokens and read the machine-in-the-middle root certificate through an unauthenticated localhost HTTP and SignalR RPC channel.

Risk And Classification

Primary CVSS: v3.1 7.7 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS: 0.000870000 probability, percentile 0.003300000 (date 2026-09-29)

Problem Types: CWE-306 | CWE-306 CWE-306: Missing Authentication for Critical Function

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.7HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1CNACVSS7.7HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Progress Software Progress Telerik Fiddler Everywhere affected 1.0.0 8.2.0 custom Not specified

References

ReferenceSourceLinkTags
www.telerik.com/fiddler/fiddler-everywhere/documentation/knowledge-base/kb-se... [email protected] www.telerik.com
www.telerik.com/fiddler/fiddler-everywhere/documentation/knowledge-base/kb-se... MITRE www.telerik.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Ezinne Kalu (github.com/zikk090) (en)

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