CVE-2025-25255Network attack vector

Domain-fronting protection bypass via crafted HTTP requests

Published Oct 14, 2025 · Updated Oct 14, 2025

Improper protocol checks in FortiOS and FortiProxy explicit web proxy allow remote attackers to bypass domain-fronting protection. Fortinet has not disclosed the exact HTTP parsing or comparison error that causes crafted requests to pass the protection check. The explicit web proxy must be enabled and reachable; exploitation alters proxy policy enforcement without disclosing data or interrupting service.

CVSS severity4.3
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper protocol checks in FortiOS and FortiProxy explicit web proxy allow remote attackers to bypass domain-fronting protection. Fortinet has not disclosed the exact HTTP parsing or comparison error that causes crafted requests to pass the protection check. The explicit web proxy must be enabled and reachable; exploitation alters proxy policy enforcement without disclosing data or interrupting service.

The record

CVE
CVE-2025-25255
Published
Oct 14, 2025
Updated
Oct 14, 2025
Vendor
Fortinet
Product
FortiOS
Classifications
CWE-358, T1090.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 14, 2025Record 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=7.6.0 <=7.6.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fortinet · FortiOSversion=7.6.0 <=7.6.3
Fortinet · FortiProxyversion=7.0.1 <=7.0.21; version=7.2.0 <=7.2.15; version=7.4.0 <=7.4.11; version=7.6.0 <=7.6.3

Published CVSS scores

4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-358Improperly Implemented Security Check for Standard
T1090.004Domain Fronting

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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