February 23, 2026 Source: BleepingComputer 2 min read · 570 words

CISA: Recently patched RoundCube flaws now exploited in attacks

CISA: нещодавно виправлені вразливості RoundCube тепер експлуатуються в атаках

CISA just confirmed that two Roundcube Webmail vulnerabilities are being actively exploited in the wild. Three weeks. That's how long U.S. federal agencies have to patch, which tells you everything you need to know about severity.

According to BleepingComputer, these aren't theoretical threats anymore—they're real CISA cyber attack incidents happening right now against actual organizations. When CISA issues a binding operational directive with that kind of deadline, it means attackers are already weaponizing the code.

Breaking It Down

Let's be clear about what this means. Roundcube is open-source webmail software that powers email access for tons of organizations—from small businesses to enterprises. It's everywhere. And if you're running an unpatched instance, you're essentially leaving your front door open with a sign that says "Come on in."

The vulnerabilities were patched recently, which means they weren't zero-days sitting unknown in some researcher's vault. Someone found them, fixed them, and then—within days—threat actors started exploiting them against systems running older versions.

This is particularly nasty because most organizations don't patch webmail software at the speed they patch, say, operating systems. Email feels secondary until it becomes your attack vector.

BleepingComputer reported that CISA cyber security officials have enough visibility into active exploitation to issue this directive with confidence. That's the kind of intel they don't usually share unless they've seen it themselves across federal networks or partner organizations.

The Technical Side

Here's where it gets technical. Without diving into exploit code, these Roundcube flaws likely fall into categories like authentication bypass or remote code execution—the types of vulnerabilities that let attackers skip right past login screens or execute commands on your server. Think of it like someone finding a service entrance around the back instead of using the front door everyone's watching.

Roundcube's architecture makes it a prime target. It's written in PHP, runs on web servers, and handles sensitive credentials and email data.

And that combination is catnip for attackers. One successful exploitation could give you access to every email account on that server.

Who's Affected

Federal agencies are getting the mandate, sure. But here's the thing—if your organization runs Roundcube, you're affected too. This isn't a "government problem." Educational institutions, healthcare providers, hosting companies, nonprofits—anyone using Roundcube webmail is in scope.

The real question is: how many organizations out there are running vulnerable versions without even knowing it?

Organizations that auto-update might be fine. Those managing updates manually? They're the ones CISA cyber security teams are worried about. And frankly, that's probably most of them.

What To Do Now

First: check what you're running. Log into your Roundcube instance and verify the version number. Compare it against the patched releases. Don't know your version number? That's actually a security problem you should fix regardless.

Second: patch immediately. Not "this week." Not "next sprint." The patches exist. Apply them. If you're running Roundcube in a containerized environment, rebuild your images. If it's on a traditional server, download the latest version and follow the upgrade documentation.

Third: if you can't patch immediately, consider disabling Roundcube until you can, then route users to a patched instance or a different webmail client temporarily. It's disruptive, but less disruptive than a compromised email server.

Fourth: implement monitoring. Check your access logs for unusual activity targeting Roundcube endpoints. Look for POST requests to suspicious paths, failed authentication attempts from unusual sources, or any signs of reconnaissance.

And finally—think about whether you even need Roundcube anymore. Modern IMAP clients, mobile apps, and cloud-based email are more secure and require less maintenance. Sometimes the best patch is architecture.

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