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CVE-2023-36556VulnerabilityPublished Updated

CVE-2023-36556: Fortinet FortiMail · Escalation of privilege

Affects Fortinet FortiMailSource CVE Database V5

0

Not known to be exploited · CVSS 8.6 High.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
8.6High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.0% chance of exploitation in 30 days – higher than 65% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:X/RC:C

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Oct 2023

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Affected software

ProductAffectedFixed in
Fortinet FortiMailAffected
  • =7.2.0
  • =7.0.0
  • =6.4.0
  • =6.2.0
  • =6.0.0
Fixed in–

AI-suggested

1. Immediately upgrade FortiMail to the latest patched versions beyond 7.2.2, 7.0.5, or 6.4.7 as provided by Fortinet once available. 2. Until patches are applied, restrict access to the FortiMail webmail interface to trusted networks or VPNs to reduce exposure. 3. Implement strong multi-factor authentication (MFA) for all FortiMail users to reduce risk from compromised credentials. 4. Monitor FortiMail logs for unusual access patterns or multiple account access attempts from single authenticated sessions. 5. Conduct regular audits of user permissions and session management configurations to ensure proper authorization controls. 6. Employ network-level protections such as web application firewalls (WAFs) with custom rules to detect and block suspicious crafted HTTP/HTTPS requests targeting FortiMail. 7. Educate users about credential security and phishing risks to prevent initial account compromise. 8. Coordinate with Fortinet support for any available workarounds or mitigations until official patches are deployed.

Description

CVE-2023-36556 is a high-severity escalation of privilege vulnerability in Fortinet FortiMail webmail versions 6.0.0 through 7.2.2. It allows an authenticated attacker to access other users' accounts within the same web domain by exploiting incorrect authorization via crafted HTTP/HTTPS requests. The vulnerability does not require user interaction but does require the attacker to have valid credentials. Exploitation can lead to full compromise of confidentiality, integrity, and availability of email communications. No public exploits are currently known. European organizations using affected FortiMail versions are at risk, especially those with large deployments of Fortinet products.

References

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