CVE-2026-86158

EUVD-2026-88649
Missing 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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
ProgressSoftwareCNA
7.7 HIGH
LOCAL
LOW
NONE
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 0.33%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
progresstelerik_fiddler_everywhere
1.0.0 ≤
𝑥
< 8.2.0
CNA
Common Weakness Enumeration
References
https://www.telerik.com/fiddler/fiddler-everywhere/documentation/knowledge-base/kb-security-exposed-dangerous-method-or-function-cve-2026-aaaaa