# CVE-2026-104657: Missing Integrity Verification in Progress Software Fiddler Download & Setup Skill

Status: published. Published: 2026-11-06. Updated: 2026-11-09.

Missing integrity verification in the Progress Software Fiddler Download and Setup Skill on Linux, macOS, and Windows which allows an attacker to compromise or influence a release component and execute attacker-controlled code when a user runs the skill. On macOS, the skill stages the package at a predictable path and installs it with administrator privileges, which may allow code execution with root privileges after user approval. A local process may also replace the staged macOS package while the skill waits for approval.

## Remediation

- workaround: Do not run the affected skill version. Install Fiddler manually from the official distribution source, verify the downloaded artifact's publisher signature and available checksum, and on macOS use a per-user DMG installation without administrator privileges. (source: CNA: ProgressSoftware)

## Affected products and versions

- Progress Software / Fiddler Download & Setup Skill: ≥ 0; < 8.3.0 (affected, semver). Source: CNA: ProgressSoftware

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H; source: CNA: ProgressSoftware

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H; source: NVD: security@progress.com

- CISA KEV: No listing in collected sources

- EPSS: 0.17% as of 2026-11-08; percentile 6.34%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-494, CWE-377

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://www.telerik.com/fiddler/fiddler-everywhere/documentation/knowledge-base/kb-security-missing-download-integrity-verification-cve-2026-104657 (CNA: ProgressSoftware; vendor-advisory)

- https://www.telerik.com/fiddler/fiddler-everywhere/documentation/knowledge-base/kb-security-missing-download-integrity-verification-cve-2026-104657 (security@progress.com)

## Provenance

- CNA: ProgressSoftware: https://www.cve.org/CVERecord?id=CVE-2026-104657; retrieved 2026-11-09; source updated 2026-11-09

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104657; retrieved 2026-11-07; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-104657; retrieved 2026-11-09; source updated Not reported

Revision: cc576e17f6e1e4c8a0bdc7d14936615b64568581b50c353e99b815af12384830

Canonical: https://y2.dev/cve/CVE-2026-104657

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