CVE
A improper neutralization of argument delimiters in a command ('argument injection') vulnerability in Fortinet FortiMail 8.0.0 through…
Affects FortiMail 8.0.0 to 8.0.2, 7.6.0 to 7.6.6, 7.4.0 to 7.4.8, and all 7.2 versions. The fix is an upgrade to 8.0.3 or later.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 8.0.3
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. FortiMail 8.0.0 through 8.0.2 FortiMail 7.6.0 through 7.6.6 FortiMail 7.4.0 through 7.4.8 FortiMail 7.2, all versions
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 29/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Fortinet FortiMail has an argument injection flaw in its administrative interface. An attacker who reaches that interface over the network and holds domain admin or admin privileges can send crafted HTTP requests to delete users of other tenant domains on a paired FortiAuthenticator, run arbitrary code or CLI commands as root, and read or write arbitrary files as root.
Read the original description
A improper neutralization of argument delimiters in a command ('argument injection') vulnerability in Fortinet FortiMail 8.0.0 through 8.0.2, FortiMail 7.6.0 through 7.6.6, FortiMail 7.4.0 through 7.4.8, FortiMail 7.2 all versions may allow an authenticated remote attacker with domain admin or admin privileges to delete users of other tenant domains on a paired FortiAuthenticator, execute arbitrary code as root or arbitrary CLI commands, and read or write arbitrary files as root via crafted HTTP requests to the administrative interface.
Who should check
Teams running Fortinet FortiMail 8.0.0-8.0.2, 7.6.0-7.6.6, 7.4.0-7.4.8 or any 7.2 release, especially those with a paired FortiAuthenticator; FortiMail Cloud customers need no action.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach14/20Affects Fortinet (an enterprise product or network appliance)
- Severity7.2/10CVSS 7.2
- No patch0/5No signal
What would change the score
- Would score about 79 if added to CISA KEV
- Would score about 74 if CISA's SSVC rates exploitation active
- Would score about 36 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
FortiMail 8.0.0 through 8.0.2 FortiMail 7.6.0 through 7.6.6 FortiMail 7.4.0 through 7.4.8 FortiMail 7.2, all versionsUpgrade to a fixed version: 8.0.3.
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-2026-126166 (A improper neutralization of argument delimiters in a command ('argument injection') vulnerability in Fortinet FortiMail 8.0.0 through…), 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-2026-126166 (entry last updated 2026-11-11):
Affected:
- Fortinet FortiMail: from 8.0.0, through 8.0.2; from 7.6.0, through 7.6.6; from 7.4.0, through 7.4.8; from 7.2.0, through 7.2.9
Fixed versions: 8.0.3.
Conditions (all must be true for the bug to be hit):
- FortiMail 8.0.0 through 8.0.2 (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-218)
- FortiMail 7.6.0 through 7.6.6 (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-218)
- FortiMail 7.4.0 through 7.4.8 (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-218)
- FortiMail 7.2, all versions (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-218)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, high-privilege login, no user action.
CISA KEV: CVE-2026-126166 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126166 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-26-218
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-2026-126166
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-2026-126166"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- Fortinet FortiMail
From 8.0.0 · through 8.0.2; From 7.6.0 · through 7.6.6; From 7.4.0 · through 7.4.8; From 7.2.0 · through 7.2.9
Evidence 3
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Link
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126166
Is CVE-2026-126166 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
What does this mean?
An authenticated attacker can inject extra arguments into a FortiMail command. The advisory says this can delete users of other tenant domains on a paired FortiAuthenticator, run arbitrary code as root or arbitrary CLI commands, and read or write arbitrary files as root.Source: fortiguard.fortinet.com
Which versions are affected by CVE-2026-126166?
FortiMail: from 8.0.0 through 8.0.2; from 7.6.0 through 7.6.6; from 7.4.0 through 7.4.8; from 7.2.0 through 7.2.9.Source: cve.now feed data
Am I affected, and how do I check?
Affected versions are FortiMail 8.0.0 through 8.0.2, 7.6.0 through 7.6.6, 7.4.0 through 7.4.8, and all 7.2 versions. Compare the installed FortiMail version against these ranges, and note whether FortiMail is paired with a FortiAuthenticator.Source: fortiguard.fortinet.com
How do I fix CVE-2026-126166?
Upgrade to 8.0.3 or above, as stated in Fortinet's advisory. The advisory gives no workaround.Source: fortiguard.fortinet.com