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A url redirection to untrusted site ('open redirect') vulnerability in Fortinet FortiAuthenticator 8.0.0 through 8.0.3, FortiAuthenticator…

CVE-2026-121526EUVD-2026-123898

5.8MediumCNA
Exploited
No known exploitation
Fix
See vendor advisory
Who is exposed
Not reported
Published
Last modified
Reference
Last checked
32/100 · provisional
None on Exploit-DB, Metasploit or GitHub

Summary

Fortinet FortiAuthenticator is affected by an open redirect flaw that lets an unauthenticated attacker send a crafted HTTP request that redirects a user to an untrusted site. Exploiting it requires the victim to take an action, such as clicking a malicious link, and the attacker can be reached remotely over the network.

Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.

Read the original description

A url redirection to untrusted site ('open redirect') vulnerability in Fortinet FortiAuthenticator 8.0.0 through 8.0.3, FortiAuthenticator 6.6.0 through 6.6.10 may allow an unauthenticated attacker to perform an open redirect attack via crafted HTTP requests.

cve.now Index

32Pcve.now Index 32 of 100 · methodology v3 · provisional
  • Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
  • Exposure7/25Reachable over the network without a login · Unknown: No advisory context yet
  • Reach14/20Affects Fortinet (an enterprise product or network appliance)
  • Severity5.8/10CVSS 5.8
  • No patch5/5No fixed version listed; see vendor advisory

What would change the score

  • Would score about 87 if added to CISA KEV
  • Would score about 82 if CISA's SSVC rates exploitation active
  • Would score about 47 if advisories confirm default setups are exposed

Check your systems with an agent

Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.

Check whether my systems are affected by CVE-2026-121526 (A url redirection to untrusted site ('open redirect') vulnerability in Fortinet FortiAuthenticator 8.0.0 through 8.0.3, FortiAuthenticator…), 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-2026-121526 (entry last updated 2026-11-11):
Affected:
- Fortinet FortiAuthenticator: from 8.0.0, through 8.0.3; from 6.6.0, through 6.6.10; from 6.5.0, through 6.5.7
Fixed versions: none listed yet.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-121526 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-121526 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-26-191
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-2026-121526
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-121526"}.

Timeline

  1. CVE published
  2. First seen by cve.now

Affected versions

  • Fortinet FortiAuthenticator

    From 8.0.0 · through 8.0.3; From 6.6.0 · through 6.6.10; From 6.5.0 · through 6.5.7

Evidence 3

Vendor advisory · 1

Establishes: Affected and fixed versions.

  1. Link

CVE record · 2

Establishes: The identifier and description.

  1. Record
  2. Record

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-121526

Is CVE-2026-121526 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: cve.now feed data

Which versions are affected by CVE-2026-121526?

FortiAuthenticator: from 8.0.0 through 8.0.3; from 6.6.0 through 6.6.10; from 6.5.0 through 6.5.7.Source: cve.now feed data