CVE-2025-6999Network attack vector

Reflected self-XSS via request sanitation bypass

Published Sep 15, 2025 · Updated Aug 10, 2026

HTTP request smuggling in the WatchGuard Fireware OS 12.0 through 12.11.2 Authentication Portal allows remote attackers to trigger reflected self-XSS. The portal handles crafted HTTP request parameters inconsistently, allowing them to bypass sanitation before their values are reflected in its response. The portal is reachable over HTTPS when firewall authentication is enabled, but WatchGuard reports no practical exploit chain with meaningful security impact.

CVSS severity6.9
Medium
EPSS probability0.45%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in the WatchGuard Fireware OS 12.0 through 12.11.2 Authentication Portal allows remote attackers to trigger reflected self-XSS. The portal handles crafted HTTP request parameters inconsistently, allowing them to bypass sanitation before their values are reflected in its response. The portal is reachable over HTTPS when firewall authentication is enabled, but WatchGuard reports no practical exploit chain with meaningful security impact.

The record

CVE
CVE-2025-6999
Published
Sep 15, 2025
Updated
Aug 10, 2026
Vendor
WatchGuard Technologies, Inc.
Product
Fireware OS
Classifications
CWE-444, CAPEC-63
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 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=12.0 <12.11.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WatchGuard Technologies, Inc. · Fireware OSversion=12.0 <12.11.3

Published CVSS scores

6.9WatchGuard Technologies, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA: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 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CAPEC-63Cross-Site Scripting (XSS)

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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