Fortinet FortiOS/FortiProxy up to 7.6.3 HTTP security check

CVSS Meta Temp Score
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CTI Interest Score
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5.2$0-$5k0.00

Summaryinfo

A vulnerability was found in Fortinet FortiOS and FortiProxy up to 7.6.3 and classified as critical. This impacts an unknown function of the component HTTP Handler. Such manipulation leads to security check. This vulnerability is traded as CVE-2025-25255. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Fortinet FortiOS and FortiProxy up to 7.6.3. Affected by this issue is an unknown code of the component HTTP Handler. The manipulation with an unknown input leads to a security check vulnerability. Using CWE to declare the problem leads to CWE-358. The product does not implement or incorrectly implements one or more security-relevant checks as specified by the design of a standardized algorithm, protocol, or technique. Impacted is confidentiality, integrity, and availability. CVE summarizes:

An Improperly Implemented Security Check for Standard vulnerability [CWE-358] vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4.0 through 7.4.11, FortiProxy 7.2 all versions, FortiProxy 7.0.1 through 7.0.22 may allow an unauthenticated proxy user to bypass the domain fronting protection feature via crafted HTTP requests.

The advisory is shared for download at fortiguard.fortinet.com. This vulnerability is handled as CVE-2025-25255 since 02/05/2025. The exploitation is known to be easy. The attack may be launched remotely. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1211.

The vulnerability scanner Nessus provides a plugin with the ID 270406 (Fortinet Fortigate Domain fronting protection bypass in explicit web proxy (FG-IR-24-372)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (270406). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

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Vendor

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.2

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.3
NVD Vector: 🔒

CNA Base Score: 5.3
CNA Vector (fortinet): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Security check
CWE: CWE-358
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 270406
Nessus Name: Fortinet Fortigate Domain fronting protection bypass in explicit web proxy (FG-IR-24-372)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

02/05/2025 CVE reserved
10/14/2025 +250 days Advisory disclosed
10/14/2025 +0 days VulDB entry created
01/14/2026 +92 days VulDB entry last update

Sourcesinfo

Vendor: fortinet.com

Advisory: FG-IR-24-372
Status: Confirmed

CVE: CVE-2025-25255 (🔒)
GCVE (CVE): GCVE-0-2025-25255
GCVE (VulDB): GCVE-100-328304

Entryinfo

Created: 10/14/2025 18:38
Updated: 01/14/2026 15:17
Changes: 10/14/2025 18:38 (55), 10/16/2025 21:39 (20), 10/18/2025 18:49 (2), 12/09/2025 21:17 (5), 01/14/2026 15:17 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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