3 Recently Patched Fortinet FortiSandbox Vulnerabilities in Hacker Crosshairs

Three recently patched Fortinet FortiSandbox vulnerabilities are being targeted in the wild, according to exploit intelligence company Defused. Defused’s honeypots have been seeing attempts to exploit CVE-2026-39808, CVE-2026-39813, and CVE-2026-25089.  CVE-2026-39813 and CVE-2026-39808 were both rated ‘critical severity’ and patched in April. The former allows an attacker to bypass authentication, while the latter is an OS command injection flaw that can be exploited to execute arbitrary code or commands.  CVE-2026-25089 was patched by Fortinet with its June 2026 Patch Tuesday updates. It allows a remote, unauthenticated attacker to execute arbitrary commands on vulnerable appliances. Exploitation of CVE-2026-39808 was independently observed by KEVIntel on June 12. Both Defused and KEVIntel reported seeing attacks targeting CVE-2026-39813 on June 15.  Defused noted that the exploit for CVE-2026-25089 appears to have been created using AI and did not work when first observed by the company.  Defused recently also saw exploitation of two Fortinet FortiClient EMS vulnerabilities tracked as CVE-2026-21643 and CVE-2026-35616. Compromised Fortinet firewalls Separately, SOCRadar has detected more than 30,000 compromised Fortinet firewalls that expose corporate networks to hacking. The campaign has been dubbed FortiBleed. According to the security firm, a threat actor has been systematically hacking Fortinet firewalls and VPN gateways, compiling a database of verified credentials that can be used to access them. The compromised systems belong to companies and government organizations across more than 190 countries. Many of the devices are located in India and the United States. “The attackers scan the internet for Fortinet devices, try a curated list of known passwords against each one, and record every successful login,” SOCRadar explained. “Once a device is compromised, they use it as a listening post, monitoring traffic passing through and collecting any additional credentials that flow by. Those freshly collected passwords are then fed back into the scanner to compromise even more devices. The system feeds itself.” The threat actor left its server exposed, enabling researchers to collect data on its infrastructure and targets. “Among the recovered data were credentials for what appears to be a defense industry VPN endpoint, suggesting the group’s ambitions extend beyond purely financial targets,” SOCRadar noted. While the company has yet to attribute the attack to a known threat actor, it believes the hackers are likely Russian speakers.  Related: Fortinet, Ivanti Patch Critical Vulnerabilities Related: Fortinet Patches High-Severity Vulnerabilities Related: Fortinet Patches Exploited FortiCloud SSO Authentication Bypass WRITTEN BY Eduard Kovacs Eduard Kovacs (@EduardKovacs) is senior managing editor at SecurityWeek. He worked as a high school IT teacher before starting a career in journalism in 2011. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering. More from Eduard Kovacs Cal Water Investigating Iranian Hackers’ Claims Cisco Patches Another SD-WAN Zero-Day Exploited in Attacks Ransomware Attack Shuts Down Mills of Australia’s Second-Largest Sugar Producer Chinese Hackers Target Medical, Military, and AI Research in North America Ozempic Maker Novo Nordisk Says Hackers Breached IT Systems Maine Disables Data Breach Portal Due to Fake Submissions  Industry Reactions to Claude Fable 5: Feedback Friday Anthropic Disputes Fable 5 AI Jailbreak Latest News Joomla, LiteSpeed Vulnerabilities Exploited in Attacks iRhythm Confirms Data Stolen in Hack Hacker Conversations: Isira Adithya, the Evolution of an Ethical Hacker Magnitude Emerges From Stealth Mode With $10 Million in Funding AI and Cybersecurity – Everything You Wanted to Know, But Were Afraid to Ask Endpoint Security Startup Ent Emerges From Stealth With $100 Million Seed Round Cybercrime Group Claims Novo Nordisk Hack Can CISOs Trust Their Applications? TrustCloud Wants to Replace the Questionnaire Trending Webinar: How Modern Breaches Bypass MFA And Evade Detection June 17, 2026 Today’s attackers are no longer breaking in — they’re logging in. Join this live webinar as we break down the modern identity attack chain and examine how recent breaches exploited weaknesses in authentication, identity verification, and access management processes. Register Webinar: Modern Exposure Validation In The AI Era June 24, 2026 AI has accelerated both sides of the fight. Adversaries are weaponizing vulnerabilities faster, while defenders are racing to ship detections and configurations. Join this live webinar as we explore how to prove your controls actually hold against new threats, map your security maturity, and unite breach simulation with automated pentesting into a single, coordinated program. Register People on the Move Stephen Garcia has been named Chief Information Security Officer at BreachRx. Kasper Lindgaard has been appointed Vice President of Security Strategy at CoreView. Chaim Mazal has been named Chief Information Security Officer at GitLab. More People On The Move Expert Insights After AI Reaches Production: 12 Ways Security Teams Can Take Control Security teams need more than visibility into AI applications, they need a repeatable framework for monitoring, investigating, and defending them in production. (Joshua Goldfarb) Everybody Is Vibe Coding But Nobody Told The Security Team AI-driven development is not something organizations can or should block. But it must be governed. (Danelle Au) The Zero-Knowledge Threat Actor And The End Of Responsible Disclosure AI can help attackers generate malware, create malicious payloads, bypass simple security checks, and convert vague malicious intent into functional code. (Etay Maor) Raising The Cybersecurity Stakes: Ante Up For The Agentic Era CISOs are now facing machine-speed attacks and asking, “How do I agent?” The industry must provide remediation at scale. (Nadir Izrael) Caught Off Guard: Securing AI After It Hits Production As enterprises rush AI projects into production, security teams are increasingly being forced into reactive mode. (Joshua Goldfarb) Flipboard Reddit Whatsapp Email