# CVE-2025-62826: Fortinet FortiOS and FortiProxy HTTP Response Splitting in captive portal

Source: https://junglewise.ai/threats/cve-2025-62826-fortinet-fortios-and-fortiproxy-http-response-splitting-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-14. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2025-62826 · Severity: low · CVSS 3.1 · Published 2026-07-14

A security vulnerability exists in the captive portal authentication system of Fortinet firewalls and web proxies. An attacker who can intercept a user's login request could inject malicious data into the web response, potentially leading to session manipulation or further web-based attacks. This issue primarily affects organizations using captive portals for guest or user network access.

Technologies: [Fortinet FortiOS](https://junglewise.ai/threats/technologies/fortios), [Fortinet FortiProxy](https://junglewise.ai/threats/technologies/fortiproxy). Vendors: [Fortinet](https://junglewise.ai/threats/vendors/fortinet).

## Quick answers

**Is CVE-2025-62826 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-62826 being exploited in the wild.

**How severe is CVE-2025-62826?** Low severity, with a CVSS score of 3.1, published 14 July 2026.

**Which products and versions are affected?** Fortinet FortiOS 7.6.0 through 7.6.4, 7.4 all versions, 7.2 all versions; Fortinet FortiProxy 7.6.0 through 7.6.4, 7.4 all versions, 7.2 all versions.

**Is there a fix for CVE-2025-62826?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2025-62826 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2025-62826?** Check whether you run Fortinet FortiOS or Fortinet FortiProxy at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An HTTP Response Splitting vulnerability (CWE-113) exists in the captive portal authentication component of FortiOS and FortiProxy. The flaw is caused by improper neutralization of CRLF sequences in HTTP headers. An attacker who can perform a Man-in-the-Middle (MitM) interception of a user's authentication request can modify the request to inject arbitrary headers into the resulting HTTP response. This requires the attacker to be in a position to intercept and modify traffic (AC:H) and involves user interaction (UI:R). Fortinet recommends upgrading to FortiOS/FortiProxy version 7.6.5 or migrating from the affected 7.2 and 7.4 branches.

## Affected products

- Fortinet FortiOS 7.6.0 through 7.6.4, 7.4 all versions, 7.2 all versions
- Fortinet FortiProxy 7.6.0 through 7.6.4, 7.4 all versions, 7.2 all versions

## Timeline

- 2026-07-14: disclosed
- 2026-07-14: advisory: FG-IR-26-153 published

## References

- [https://fortiguard.fortinet.com/psirt/FG-IR-26-153](https://fortiguard.fortinet.com/psirt/FG-IR-26-153)

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- [Fortinet FortiOS numeric truncation error in BGP daemon](https://junglewise.ai/threats/cve-2026-126254-a-numeric-truncation-error-vulnerability-in-fortinet-fortios-8-0)