CVE-2026-66596Network attack vector

Arbitrary script execution in visitor browsers

Published Aug 19, 2026 · Updated Aug 19, 2026

Cross-site scripting in Stefano Lissa Newsletter before 9.3.4 allows remote attackers to execute script in a visitor browser. Patchstack and the public CVE record describe the issue only as unauthenticated XSS in versions through 9.3.3; no vendor advisory, fix diff, or public record retrieved on August 20, 2026 discloses the affected parameter, endpoint, or function. No authentication is required to place the payload, but exploitation still depends on a user loading attacker-controlled content or a crafted page, and the published impact is limited to browser-side script execution.

CVSS severity7.1
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Stefano Lissa Newsletter before 9.3.4 allows remote attackers to execute script in a visitor browser. Patchstack and the public CVE record describe the issue only as unauthenticated XSS in versions through 9.3.3; no vendor advisory, fix diff, or public record retrieved on August 20, 2026 discloses the affected parameter, endpoint, or function. No authentication is required to place the payload, but exploitation still depends on a user loading attacker-controlled content or a crafted page, and the published impact is limited to browser-side script execution.

The record

CVE
CVE-2026-66596
Published
Aug 19, 2026
Updated
Aug 19, 2026
Vendor
Stefano Lissa
Product
Newsletter
Classifications
CWE-79, CAPEC-588, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a <=9.3.3 changes=[{"at":"9.3.4","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Stefano Lissa · Newsletterversion=n/a <=9.3.3 changes=[{"at":"9.3.4","status":"unaffected"}]

Published CVSS scores

7.1PatchstackCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CAPEC-588DOM-Based XSS
T1059.007JavaScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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