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A critical vulnerability in  Bifrost , an open-source AI gateway that routes requests to more than 20 LLM providers, allows an unauthenticated attacker to run arbitrary commands on the gateway server with a single HTTP request. The flaw, tracked as  CVE-2026-90898  (CVSS score: 9.8), affects all versions of the Bifrost HTTP transport before 2.1.0 when management authentication is disabled, which is the default configuration. A fix is available in transports/v2.1.0. Yuval Moravchick of  JFrog Security Research , who discovered the flaw, said an attacker can register a stdio-type MCP client through a single unauthenticated POST to the management API endpoint /api/mcp/client. Bifrost starts the specified command immediately, before any MCP handshake, as the gateway process user. On the official Docker image, that user is appuser. Because the gateway stores API keys for every connected provider, executing commands on the gateway process grants the attack...

A zero-day proof-of-concept tool that stops Microsoft Defender from installing platform and signature updates by filling all available disk space was  published on GitHub  on September 19. The tool, called BigDiskBuster , has no patch, no CVE, and no Microsoft advisory. Its author, Abdelhamid Naceri, is a former Microsoft security researcher whose earlier Defender exploits were used in attacks. When updates are blocked, Defender keeps running, but its detection content grows stale. The researcher's screenshot shows Defender returning a generic Windows error when trying to update, but whether the failure raises an automatic alert is not clear from the proof-of-concept alone. Naceri said he was dismissed from Microsoft's Security Response Center in 2024 and has been releasing exploits without coordinating with the company since April. His first three Defender tools — BlueHammer, RedSun, and UnDefend — were all  exploited in live intrusions  before Microsoft...

Attackers are exploiting a new flaw in on-premises VeloCloud Orchestrator (VCO), the server that manages the Edge devices in a VeloCloud SD-WAN, Arista said on September 22. The flaw, tracked as CVE-2026-93952 , may allow a remote attacker with no login access to privilege internal functions and affect the VCO host. Only orchestrators set up to authenticate their Edges with certificates are exposed. As of September 22,  fixed releases  are out for the 5.2 and 6.4 release trains, but not yet for the 6.1 and 7.0 trains. Arista has already patched the Hosted and Dedicated versions of VCO. The affected releases include those that fixed a different VCO flaw, which Arista reported as  exploited in July . Arista gave the flaw a CVSS 3.1 score of 10.0. A successful attack may compromise the orchestrator and the data it manages. A compromised VCO may also give attackers access to the Edge devices it manages. Arista said the flaw "was discovered externally and is known t...

A new flaw in the Linux kernel's KVM virtualization code for ARM64 processors can leave a freed piece of host memory exposed to a guest virtual machine on hosts with nested virtualization enabled. The bug, tracked as  CVE-2026-89775 , allows a guest to read and write host kernel memory, and the researcher who found it says it can be used to escape the guest and run code on the host machine. The affected code is part of the mainline Linux kernel for ARM64, and it is fixed in Linux 6.18.51, 7.2.5, and 7.3-rc1. Nested virtualization allows a guest to run its own hypervisor, enabling it to host virtual machines. On ARM64, it is off by default. It is  an experimental boot-time mode  that needs Armv8.4 hardware with a feature called FEAT_NV2, so a plain ARM64 KVM host that never turns it on is outside the reported attack path. The flaw sits in the part of KVM that handles nested virtualization on ARM64. When a guest arranges its memory in a certain way, a size calculat...

A SharePoint Server vulnerability that Microsoft initially classified as a spoofing flaw with a CVSS score of 6.5 actually enables authenticated remote code execution, according to full technical details published today by Viettel Cyber Security researcher Dinh Ho Anh Khoa. The flaw, CVE-2026-65660 , affects SharePoint Server 2016, 2019, and Subscription Edition. Patches have been available since the  August 11 security updates , and the National Vulnerability Database scores it 8.8. Microsoft's advisory  describes CVE-2026-65660 as allowing an authorized attacker to perform spoofing and assigns no impact to integrity or availability. The CVE record that Microsoft publishes separately, updated on September 11, titles the same flaw a remote code execution vulnerability and says it allows an authorized attacker to execute code. Both records assign CWE-94, a code-injection weakness. Defenders who triaged CVE-2026-65660 based on the advisory saw a moderate spoofi...

Malware already running on a Mac can quietly take over Meta's Muse assistant and use the broad access its owner granted the app, security researcher Patrick Wardle has shown in a  proof-of-concept  released on September 21. It works by changing a hidden setting so that when the user taps the microphone and dictates a prompt, the words go to the attacker instead of Meta. The flaw is in the Mac version of Muse, and it only works if an attacker can already run code as the logged-in user. It cannot break into a Mac on its own. But Wardle told The Hacker News that a remote attacker could hijack Muse and steal its token through a ClickFix trick, which fools the user into running a single command with nothing to download or install. Muse is the personal AI agent Meta  launched this month  in the United States. Once a user turns it on, it can work across their files, email, messages, calendar, shopping and smart-home apps, using whatever access the person chooses to g...

A new flaw in WordPress core let an anonymous visitor leave a comment that planted a hidden script on the page. If a logged-in administrator later opened that page, the script could run code on the site's server. WordPress fixed the flaw, tracked as  CVE-2026-93485  and called " Comment2Shell ," on September 17 in  version 7.1.1  and told site owners to update right away. There is no sign it has been used in attacks, and it is not on the U.S. government's list of actively exploited software flaws. Patchstack, the company that assigned that identifier, rated the flaw 7.1 out of 10 on the CVSS scale. WordPress checks a comment for dangerous HTML when it is saved, then reformats it when the page is shown, and the flaw sat in the gap between those two steps. Rafie Muhammad, the security researcher who reported the bug, laid out the full chain in  a write-up  on September 21. The trick was a line break placed inside the attribute of an allowed HTML tag ...

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Monday added a now-patched security flaw impacting Zyxel GS1900 series switches to its Known Exploited Vulnerabilities ( KEV ) catalog, citing evidence of active exploitation. The vulnerability, tracked as CVE-2026-7273 (CVSS score: 8.8), is a stack-based buffer overflow vulnerability that could result in arbitrary operating system (OS) command execution. "A stack-based buffer overflow vulnerability in the CGI program of the Zyxel GS1900 series switch firmware could allow a LAN-based, unauthenticated attacker to exploit the flaw and potentially execute OS commands via a crafted HTTP request," Zyxel said in an advisory released in June 2026.  The issue has been addressed in the following versions -

A browser. A plugin. A package. A login screen. Normal stuff. That is basically the problem this week. The trouble keeps showing up inside things people already trust: code that takes a bad turn, old payloads coming back, exposed systems, weak checks, fake fixes, and attack paths that look almost too easy. Even the research side is getting messy, with more findings, more automation, and not always more clarity. Nothing here needs much drama. Just a lot of small doors left open. Here’s what happened. ⚡ Threat of the Week Cisco Warns of Actively Exploited ISE Auth Bypass — Cisco warned of a fresh maximum-severity security flaw impacting Identity Services Engine (ISE) that has come under active exploitation. The vulnerability, tracked as CVE-2026-76460 (CVSS score: 10.0), could allow an unauthenticated, remote attacker to bypass authentication. "This vulnerability is due to insufficient authentication control on an API endpoint," Cisco said. "An attacker could exp...

Three researchers at the security firm  Hacktron  used Anthropic's Claude Opus 5 to chain two flaws and take over the ChatGPT and Codex accounts of several OpenAI employees, then reach an internal OpenAI code repository. The chain began with a bug in the software that runs OpenAI's public help forum and moved through a weakness in OpenAI's own login system. This was security research, not a real-world attack: the team reported the flaws to OpenAI, proved the access with a harmless pull request, and then stopped. From the first look, that internal access took under 72 hours. OpenAI confirmed a fix about 14 hours after the report, according to Hacktron, and on September 1 paid the team a $6,500 bounty. OpenAI said the award "recognizes the OpenAI-side finding, not the actions against Discourse," the open-source software that runs the forum. Testing the forum itself was outside its bug bounty program. OpenAI has not publicly described the login flaw, and it ...

A new CVE drops. Your scanner finds it. The severity score looks ugly. But that still does not answer the question that matters: Can it actually be exploited in your environment? Mythos-class AI is compressing the time between disclosure and working exploitation, while many security programs still validate risk on weekly or quarterly cycles. The dangerous gap is no longer just technical. It is measured in time. 📅 Save Your Spot Today: How to Prove You're Ready for Mythos-Class Attacks . Can’t join live? Register anyway. We’ll send the webinar recording after the session, so you can watch it later, whenever it fits your schedule, and still see the full, fresh CVE-to-validation workflow. Stop prioritizing on severity alone A high score tells you a vulnerability could be serious. It does not prove that an attacker can use it against you. Security teams need faster answers: Is the affected asset exposed? What attack techniques does exploitation require? Do ...

SolarWinds has released security updates to address a high-severity flaw in Access Rights Manager (ARM) that, if successfully exploited, could lead to an unauthenticated remote code execution vulnerability. The vulnerability, tracked as CVE-2026-28326 , is rated 8.8 out of 10.0 on the CVSS scoring system. The issue affects all versions of Access Rights Manager 2026.2 and prior. "SolarWinds Access Rights Manager was reported to be affected by an unauthenticated remote code execution vulnerability," SolarWinds said in an advisory released on September 17, 2026. "The issue stems from a hard-coded static key." The company credited Armadin security researcher Kai Huang with discovering and reporting the flaw, which has been patched in ARM 2026.2.1 . SolarWinds makes no mention of the vulnerability being exploited in the wild. The development comes nearly two months after the company shipped fixes for a critical flaw impacting Web Help Desk (WHD) (CVE-2026-28323...

A critical vulnerability impacting Orkes Conductor is being actively exploited in the wild, according to Fortinet. The vulnerability in question is CVE-2026-58138 (CVSS v3.1 score: 9.8/CVSS v4 score: 9.3), which relates to a case of unauthenticated remote code execution. "Orkes Conductor 3.21.21 before 3.30.2 contains an unauthenticated remote code execution vulnerability that allows remote attackers to execute arbitrary OS commands by submitting inline workflow definitions containing malicious JavaScript or Python expressions to the workflow API endpoint prior to authentication," a description of the flaw on the NIST National Vulnerability Database (NVD) reads. "Attackers can exploit unsandboxed GraalVM evaluators configured with HostAccess.ALL or allowAllAccess(true) through INLINE, LAMBDA, DO_WHILE, and SWITCH task types to invoke arbitrary system commands via Java reflection or direct subprocess calls." In an outbreak alert issued this week, Fortinet ...

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added three security flaws impacting the Linux kernel to its Known Exploited Vulnerabilities ( KEV ) catalog, citing evidence of active exploitation. The vulnerabilities are listed below - CVE-2025-39682 (CVSS score: 9.8) - An improper check for unusual or exceptional conditions vulnerability in the TLS receive path that could allow local authenticated users to trigger memory disclosure or denial-of-service (DoS). CVE-2026-53266 (CVSS score: 8.8) - An out-of-bounds write vulnerability in the ebtables Source Network Address Translation (SNAT) Address Resolution Protocol (ARP) rewrite path that could allow a local attacker to trigger unintended system behavior, DoS, or local privilege escalation. CVE-2025-39964 (CVSS score: 7.8) - A race condition vulnerability that could allow concurrent writes to the same AF_ALG socket, allowing a local attacker to crash the system or corrupt cryptographic ope...

A security researcher has released working exploit code for four Linux kernel flaws that each let a local user gain root, the highest level of access on a machine. Kernel maintainers have fixed all four over the past few weeks, so a system running an up-to-date kernel is not affected. But the exploit code is now public, and any machine still running an older kernel should be updated. The flaws are called DirtyAH6 , TUNderflow , PPPoEject , and DiagSpill . Researcher Asim Manizada found them and reported them to the Linux kernel security team in mid-July. He published a technical  write-up  with working exploits on September 18, after a coordinated hold with Linux distributions so the fixes could be released first. So far, there are no reports of the four being used in real-world attacks. The exploits are Manizada's own, are tuned to specific kernel builds, and can crash a machine, so they are meant for isolated test systems. Still, public exploit code raises the ris...

WordPress today released patches to fix a new set of vulnerabilities in its core software, one of which could allow a crafted web link, opened by a logged-in administrator, to install a theme from the official WordPress.org directory without anyone clicking Install. The security firm pwn.ai , whose researchers reported the flaw, calls the attack chain Click2Shell . On its own the flaw only installs a real theme that the attacker picks, but the security research team showed it could be combined with a separate weakness in a theme to run the attacker's own code on the server.  The fix shipped on September 17 in WordPress 7.1.1 . Because this is a security release, WordPress advises updating right away. There is no sign the flaw has been used in real attacks. The installed theme stays switched off, so the site's own appearance does not change and nothing looks wrong. Reaching code execution needed a second, separate flaw in the theme that was installed. As pwn.ai wrote of t...

Microsoft has released fixes for a maximum-severity security flaw in Azure AI Foundry that could be exploited to achieve privilege escalation. No customer action is required. The vulnerability, tracked as CVE-2026-85889 , carries a CVSS score of 10.0. "Missing authentication for critical function in Azure AI Foundry allows an unauthorized attacker to elevate privileges over a network," Microsoft said in a Thursday advisory. Azure AI Foundry, also called Microsoft Foundry, is an enterprise platform designed to build, deploy, and manage generative artificial intelligence (AI) applications and agents. The Windows maker credited security researcher Rémy Marot (@R_Marot) for discovering and reporting the flaw. There is no evidence that the issue has been exploited in the wild. Also patched by Microsoft in recent days are a number of other critical flaws -

A flaw in four widely used AI coding agents lets someone who controls a plugin's code repository swap the plugin an agent installs for a malicious one, even when the agent locked that plugin to a specific reviewed version, security firm  Air Security said on Thursday . The firm said Anthropic has patched the flaw in Claude Code 2.1.179 and OpenAI in Codex 0.146.0, that GitHub Copilot has no fix, and that Google will not patch the Gemini CLI, which it is retiring. The agents install add-ons called plugins from online marketplaces. To stay safe, a marketplace locks each plugin to a single reviewed version by its commit hash, a long string that identifies an exact snapshot of the code. Air found that the agents fetch that snapshot but never check that the code they end up with actually matches it. A branch is a named line of code in a repository. On a code host that lets someone create a branch whose name is made to look like the commit hash, the owner of a plugin's reposit...

A critical vulnerability in Check Point's Security Management and Log Servers could allow an attacker without login credentials to run code as root on those servers over the network. The Security Management Server is the system that controls firewall policy and administrator access. Check Point has released a fix through its LivePatch update channel and says it has no indication that the flaw has been exploited. Check Point told The Hacker News that the vulnerable path runs only through the Trusted Clients setting, which controls which hosts may connect to the management server through SmartConsole. The flaw, tracked as CVE-2026-91843 and rated 9.8 out of 10 on the CVSS scale by Check Point, is a stack overflow in the login process, which handles requests before a user is authenticated. Internet scanning company Censys said the overflow is triggered by a login request that carries a very long username. Check Point said in a notice on its  CheckMates community  on...

Attackers keep finding new keys. The funny part is that defenders keep inventing where to store them. This week, those keys sit in AI tools, exposed services, old bugs, weak logins, and software sold like a monthly subscription. Some attacks use new tricks. Others just reuse what was already lying around. Both work often enough. So the threat landscape is not getting cleaner. It is just getting more places to make the same mistake. Here’s what showed up this week. The threats change every week. Subscribe, and we’ll alert you when each new ThreatsDay Bulletin is out.