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Introduction
Fortinet products are once again at the center of global cybersecurity concerns after multiple critical vulnerabilities were observed being exploited in real-world attacks. Security researchers have identified active attempts targeting recently patched flaws in FortiSandbox, while a separate large-scale operation known as FortiBleed has reportedly compromised tens of thousands of Fortinet firewalls and VPN gateways worldwide.
The developments highlight a growing challenge for organizations that rely on network security appliances. Devices designed to protect enterprise environments are increasingly becoming prime targets for cybercriminals seeking privileged access to corporate and government networks. The latest findings suggest that threat actors are moving quickly to weaponize newly disclosed vulnerabilities, leaving little room for delayed patching.
Active Exploitation Targets Recently Patched FortiSandbox Flaws
Security researchers at Defused have reported observing active exploitation attempts against three recently patched vulnerabilities affecting Fortinet FortiSandbox appliances.
The vulnerabilities include CVE-2026-39808, CVE-2026-39813, and CVE-2026-25089, all of which can potentially provide attackers with powerful access to affected systems. Honeypot infrastructure deployed by Defused detected attackers probing and attempting to exploit these weaknesses shortly after public disclosure.
The rapid appearance of exploitation activity demonstrates how quickly cybercriminals react to newly published security advisories. Once technical details become available, attackers often reverse-engineer patches to identify vulnerable systems that remain unprotected.
Critical Authentication Bypass Creates Serious Risk
Among the most dangerous flaws is CVE-2026-39813, a critical vulnerability that enables authentication bypass.
Authentication mechanisms serve as the first line of defense in security products. When attackers can bypass login requirements entirely, they effectively gain direct access to protected functionality without valid credentials.
Such vulnerabilities are particularly attractive because they eliminate the need for password theft, phishing campaigns, or credential brute-forcing. Instead, attackers can immediately focus on gaining deeper access and establishing persistence.
Command Injection Vulnerability Enables Remote Code Execution
Another critical issue, CVE-2026-39808, allows operating system command injection.
This type of vulnerability enables attackers to execute arbitrary commands directly on the underlying operating system. In practical terms, successful exploitation may allow malicious actors to install malware, deploy backdoors, create unauthorized accounts, steal sensitive information, or pivot deeper into internal networks.
Command injection flaws remain among the most dangerous classes of vulnerabilities because they often provide attackers with extensive control over targeted systems.
Newly Patched June Vulnerability Also Under Attack
The third vulnerability, CVE-2026-25089, was addressed during
Researchers observed attempts to exploit this vulnerability shortly after patches became available. The flaw allows remote, unauthenticated attackers to execute arbitrary commands on vulnerable FortiSandbox appliances.
Interestingly, Defused noted that the initial exploit sample appeared to have been generated with artificial intelligence assistance and did not function correctly during its earliest observed stages.
The incident reflects a growing trend in cybercrime where attackers leverage AI technologies to accelerate exploit development and vulnerability research.
Security Researchers Confirm Real-World Activity
Independent threat intelligence sources have confirmed portions of the observed activity.
KEVIntel reportedly detected exploitation attempts targeting CVE-2026-39808 on June 12, while attacks against CVE-2026-39813 were observed by both Defused and KEVIntel on June 15.
Multiple independent observations strengthen confidence that these vulnerabilities are being actively targeted rather than merely discussed within security communities.
Organizations running FortiSandbox appliances should assume that attackers are actively scanning the internet for vulnerable systems.
FortiClient EMS Vulnerabilities Also Being Exploited
Defused additionally reported exploitation attempts involving two FortiClient EMS vulnerabilities tracked as CVE-2026-21643 and CVE-2026-35616.
The activity suggests that attackers are not focusing on a single Fortinet product line. Instead, threat actors appear to be evaluating multiple components across the Fortinet ecosystem in search of exploitable entry points.
This broader targeting pattern increases pressure on administrators to maintain comprehensive patch management programs across all deployed security infrastructure.
FortiBleed Campaign Exposes More Than 30,000 Systems
While organizations grapple with newly exploited vulnerabilities, a separate security concern has emerged through a campaign known as FortiBleed.
Researchers at SOCRadar reported discovering more than 30,000 compromised Fortinet firewalls and VPN gateways that could expose organizations to unauthorized access and network surveillance.
The scale of the operation suggests a highly automated infrastructure capable of identifying, validating, and cataloging compromised devices across numerous regions and industries.
Affected organizations reportedly span more than 190 countries, highlighting the global nature of the threat.
How FortiBleed Allegedly Operates
According to researchers, the attackers systematically scan the internet searching for exposed Fortinet devices.
Rather than relying exclusively on software vulnerabilities, the operation reportedly uses curated collections of known passwords and previously exposed credentials to identify systems vulnerable to unauthorized access.
Once a successful login occurs, the compromised device allegedly becomes a monitoring point capable of collecting additional credentials passing through network traffic.
These newly harvested credentials are then recycled into future attack cycles, creating a self-sustaining ecosystem that expands the campaign’s reach over time.
This methodology demonstrates how credential security remains just as important as software patching.
Government and Enterprise Networks Potentially Impacted
Researchers reported that compromised devices belong to a diverse range of organizations, including businesses and government entities.
Particularly concerning was the discovery of credentials allegedly associated with what appeared to be a defense-sector VPN endpoint.
If confirmed, such findings would indicate that the campaign’s objectives extend beyond simple financial crime and may include strategic intelligence gathering.
The targeting of critical infrastructure, government environments, and defense-related systems remains a recurring theme among advanced cybercriminal and nation-state operations.
Researchers Gain Visibility Into Threat Infrastructure
An unusual aspect of the investigation emerged when the threat actor reportedly exposed part of its own server infrastructure.
This operational mistake provided researchers with an opportunity to analyze internal data, infrastructure components, and targeting information associated with the campaign.
Cybersecurity investigations often benefit from such accidental exposures, allowing defenders to better understand attacker behavior, operational methods, and victim selection strategies.
The information gathered may assist future defensive efforts and threat attribution investigations.
Russian-Speaking Actors Suspected
Although researchers have not definitively attributed the campaign to a known threat group, SOCRadar believes the operators are likely Russian speakers.
Attribution remains one of the most difficult aspects of cybersecurity investigations. Language indicators, infrastructure choices, operational timing, and malware characteristics can provide clues, but definitive conclusions often require extensive intelligence correlation.
For now, the identity of the actors behind FortiBleed remains uncertain.
Major Global Companies Reportedly Affected
Research conducted by Bob Diachenko and cybersecurity company Hudson Rock suggests that the campaign may have impacted devices associated with major international organizations.
Among the companies reportedly linked to affected infrastructure are Foxconn, Samsung, Comcast, Siemens, Lenovo, PwC, Accenture, and Oracle.
The presence of globally recognized organizations underscores the widespread nature of credential-based attacks and highlights the importance of securing internet-facing security appliances.
Deep Analysis: Linux Commands Reveal Why Rapid Patching Matters
Security teams responding to Fortinet-related threats often begin with visibility and asset discovery.
Administrators may use commands such as:
nmap -sV <target>
to identify exposed services and vulnerable versions.
System logs can be reviewed using:
journalctl -xe
to investigate unusual authentication activity.
Security analysts frequently inspect network connections with:
netstat -tulpn
or:
ss -tulpn
to detect suspicious communications.
Compromised devices can sometimes be identified by examining active processes:
ps aux
Unexpected scheduled tasks may be revealed through:
crontab -l
File integrity verification can be assisted using:
find / -mtime -7
to identify recently modified files.
Threat hunting teams often search for indicators of compromise using:
grep -Ri "indicator" /var/log/
Firewall configuration validation may involve:
iptables -L -n
Network traffic monitoring can be performed through:
tcpdump -i any
or:
wireshark
during forensic analysis.
The Fortinet incidents reinforce a long-standing cybersecurity reality. Security appliances themselves have become high-value targets. Attackers understand that compromising a firewall, VPN gateway, or sandbox appliance can provide access to enormous volumes of sensitive traffic. As a result, organizations must treat security infrastructure with the same urgency traditionally reserved for critical servers and domain controllers.
What Undercode Say:
The Fortinet situation illustrates how modern cyberattacks increasingly combine multiple techniques rather than relying on a single vulnerability.
Attackers are exploiting newly disclosed flaws while simultaneously leveraging stolen credentials.
This dual approach dramatically increases their chances of success.
The rapid weaponization of CVE-2026-39808, CVE-2026-39813, and CVE-2026-25089 demonstrates that patch release dates no longer provide organizations with comfortable remediation windows.
Threat actors now monitor vendor advisories in real time.
Security teams frequently underestimate how quickly adversaries reverse-engineer patches.
The mention of AI-generated exploit code is especially noteworthy.
Even though the observed exploit initially failed, the trend is significant.
Artificial intelligence is lowering technical barriers.
Attackers can now accelerate proof-of-concept creation.
Less experienced threat actors may gain capabilities previously limited to advanced researchers.
FortiBleed presents an equally concerning scenario.
Unlike software vulnerabilities, credential attacks exploit human and operational weaknesses.
Strong passwords alone are insufficient if credential reuse exists.
The self-feeding model described by researchers is particularly effective.
Each successful compromise creates opportunities for additional compromises.
This creates exponential growth.
The campaign also highlights visibility challenges.
Many organizations do not continuously monitor security appliances.
Firewalls often operate quietly for years.
Administrators may assume they remain secure once deployed.
Threat actors exploit this assumption.
The alleged involvement of government and defense-related systems raises the overall severity level.
Strategic targeting often indicates objectives beyond financial gain.
If intelligence collection is involved, long-term persistence becomes more valuable than immediate monetization.
Another important observation is the geographic distribution.
Over 190 countries being affected suggests highly automated infrastructure.
Manual operations alone would struggle to achieve such scale.
Automation remains a defining characteristic of modern cybercrime.
The exposure of attacker infrastructure is also unusual.
Operational mistakes by threat actors continue to provide valuable intelligence.
Many major investigations begin with simple configuration errors made by attackers themselves.
Organizations should focus on three priorities.
Immediate patch deployment.
Multi-factor authentication enforcement.
Continuous monitoring of administrative access.
Network security appliances should be treated as critical assets.
Every internet-facing device should undergo routine security review.
Threat hunting should extend beyond endpoints and servers.
Credential auditing should become a recurring exercise.
The Fortinet ecosystem remains widely deployed worldwide.
Because of that popularity, it will likely remain a preferred target for both cybercriminal groups and advanced persistent threat actors in the months ahead.
✅ Defused reported active exploitation attempts targeting CVE-2026-39808, CVE-2026-39813, and CVE-2026-25089.
✅ CVE-2026-39813 is described as an authentication bypass vulnerability, while CVE-2026-39808 enables OS command injection capable of arbitrary command execution.
✅ SOCRadar reported more than 30,000 compromised Fortinet firewalls and VPN gateways associated with the FortiBleed campaign, though attribution to a specific threat actor remains unconfirmed.
Prediction
(+1) Organizations will accelerate patch deployment cycles for internet-facing security appliances following increased exploitation activity.
(+1) Security vendors will invest more heavily in AI-assisted vulnerability detection and exploit analysis technologies.
(+1) Threat intelligence sharing between researchers and enterprises will improve as large-scale campaigns such as FortiBleed gain attention.
(-1) Additional Fortinet devices that remain unpatched are likely to be compromised in future attack waves.
(-1) Credential-based attacks against VPN gateways and firewall platforms will continue growing throughout the year.
(-1) AI-assisted exploit development may shorten the time between vulnerability disclosure and active exploitation even further.
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Reported By: www.securityweek.com
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