CVE-2025-66523Network attack vector

Arbitrary script execution via unsanitized URL parameters

Published Jan 20, 2026 · Updated Jan 20, 2026

Reflected XSS in Foxit eSign before 2026-01-16 allows remote attackers to execute arbitrary JavaScript through crafted links. URL parameters are inserted directly into JavaScript code or HTML attributes without context-appropriate encoding or sanitization. Execution requires an authenticated user to visit the attacker-supplied link, after which script runs in that user’s browser under the eSign origin.

CVSS severity6.1
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Foxit eSign before 2026-01-16 allows remote attackers to execute arbitrary JavaScript through crafted links. URL parameters are inserted directly into JavaScript code or HTML attributes without context-appropriate encoding or sanitization. Execution requires an authenticated user to visit the attacker-supplied link, after which script runs in that user’s browser under the eSign origin.

The record

CVE
CVE-2025-66523
Published
Jan 20, 2026
Updated
Jan 20, 2026
Vendor
Foxit Software
Product
Foxit eSign
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 20, 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=before 2026‑01‑16

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Foxit Software · Foxit eSignversion=before 2026‑01‑16

Published CVSS scores

6.1FoxitCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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')
T1204.001Malicious Link

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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