Threats / Fortinet / CVE-2020-12812
CVE-2020-12812
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Fortinet FortiOS vulnerability
Fortinet FortiOS SSL VPN contains an improper authentication vulnerability allowing attackers to bypass second-factor authentication by modifying username case, enabling unauthorized access.
Verdict
Today item, not a backlog item.
An authentication bypass in FortiOS SSL VPN permits attackers to circumvent FortiToken multi-factor authentication requirements through case manipulation of usernames. This vulnerability has been exploited in active ransomware campaigns.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
35 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.49344 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Fortinet, FortiOS. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-178 Case Sensitivity, CWE-287 Improper Authentication — weakness family: Authentication.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a login request using a username with altered case to bypass the second-factor authentication check.
Business
Unauthorized remote access to critical infrastructure and sensitive systems is gained without proper credential validation.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I establish a persistent session within the VPN environment to move laterally across the network.
Business
Attackers gain foothold for data exfiltration, system compromise, and deployment of ransomware payloads.
3
Lateral reach — past segmentation narrative 3
Attacker
I deploy ransomware across connected systems while maintaining access through the compromised VPN session.
Business
Operations are disrupted, data is encrypted, and ransom demands are issued, resulting in financial and reputational damage.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05