CVE-2026-86158

high

Assigned by CNA: progresssoftware

Published 2026-09-29 · Modified 2026-09-29

Discuss on Community Propose mitigation

CVSS v3

7.7

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

CVSS v4 NEW

—

not yet in upstream

VIR risk

7.7

Description

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.

Predictions

Exploit likelihood

75%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

References

https://www.telerik.com/fiddler/fiddler-everywhere/documentation/knowledge-base/kb-security-exposed-dangerous-method-or-function-cve-2026-aaaaa

CWEs

CWE-306

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.