# CVE-2026-59840: Fortinet FortiOS and FortiProxy buffer over-read in authd and wad daemons

Source: https://junglewise.ai/threats/cve-2026-59840-fortinet-fortios-and-fortiproxy-buffer-over-read-in-authd-and-wad  
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-2026-59840 · Severity: medium · CVSS 4.3 · Published 2026-07-14

Fortinet FortiOS and FortiProxy, which are used to manage network security and web traffic, contain a security flaw. An authenticated user could potentially view sensitive information stored in the device's memory by sending a specially crafted request. This could lead to the unauthorized disclosure of internal system data, though it does not allow for full system takeover.

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

## Quick answers

**Is CVE-2026-59840 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59840 being exploited in the wild.

**How severe is CVE-2026-59840?** Medium severity, with a CVSS score of 4.3, published 14 July 2026.

**Which products and versions are affected?** Fortinet FortiOS 7.6.0 through 7.6.2, 7.4.0 through 7.4.8, 7.2 all versions; Fortinet FortiProxy 7.6.0 through 7.6.5, 7.4.0 through 7.4.13, 7.2 all versions; Fortinet Fortisase All versions.

**Is there a fix for CVE-2026-59840?** 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-2026-59840 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-59840?** Check whether you run Fortinet FortiOS, Fortinet FortiProxy or Fortinet Fortisase 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

A buffer over-read vulnerability (CWE-126) exists in the authd and wad daemons of Fortinet FortiOS, FortiProxy, and FortiSASE. The flaw is triggered when the system processes a specially crafted request, causing it to return a portion of device memory within a redirect response. An attacker must be authenticated (PR:L) to exploit this vulnerability over the network. Successful exploitation results in information disclosure, potentially revealing sensitive data residing in the memory space of the affected processes. Patches are available in FortiOS 7.6.4, 7.4.9, and FortiProxy 7.6.6 and 7.4.14.

## Affected products

- Fortinet FortiOS 7.6.0 through 7.6.2, 7.4.0 through 7.4.8, 7.2 all versions
- Fortinet FortiProxy 7.6.0 through 7.6.5, 7.4.0 through 7.4.13, 7.2 all versions
- Fortinet FortiSASE All versions

## Timeline

- 2026-07-14: advisory: Initial publication by Fortinet

## References

- [https://fortiguard.fortinet.com/psirt/FG-IR-26-154](https://fortiguard.fortinet.com/psirt/FG-IR-26-154)

## Related threats

- [Fortinet FortiOS authentication bypass in HA command execution](https://junglewise.ai/threats/cve-2026-126259-a-missing-authentication-for-critical-function-vulnerability-in)
- [Fortinet FortiOS stack buffer overflow in WAD proxy](https://junglewise.ai/threats/cve-2026-126258-a-stack-based-buffer-overflow-vulnerability-in-fortinet-fortios)
- [Fortinet FortiOS out-of-bounds read in kernel](https://junglewise.ai/threats/cve-2026-126256-a-out-of-bounds-read-vulnerability-in-fortinet-fortios-8-0-0)
- [Fortinet FortiOS path traversal authentication bypass in SSH daemon](https://junglewise.ai/threats/cve-2026-126255-a-path-traversal-filedir-vulnerability-in-fortinet-fortios-8-0-0)
- [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)