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This Week In Security: Getting Back Up To Speed

March 6, 2026 by 11 Comments

Editor’s Note: Over the course of nearly 300 posts, Jonathan Bennett set a very high bar for this column, so we knew it needed to be placed in the hands of somebody who could do it justice. That’s why we’re pleased to announce that Mike Kershaw AKA [Dragorn] will be taking over This Week In Security! Mike is a security researcher with decades of experience, a frequent contributor to 2600, and perhaps best known as the creator of the Kismet wireless scanner.

He’ll be bringing the column to you regularly going forward, but given the extended period since we last checked in with the world of (in)security, we thought it would be appropriate to kick things off with a review of some of the stories you may have missed.

Hacking like it’s 2009, or 1996

Hello all!  It’s a pleasure to be here, and it already seems like a theme of the new year so far has bringing in the old bugs – what’s old is new again, and 2026 has seen several fixes to some increasingly ancient bugs.

Telnet

Reported on the OpenWall list, the GNU inetd suite brings an update to the telnet server (yes, telnet) that closes a login bug present since 2015 linked to environment variable sanitization.

Under the covers, the telnet daemon uses /bin/login to perform user authentication, but also has the ability to pass environment variables from the client to the host. One of these variables, USER, is passed directly to login — unfortunately this time with no checking to see what it contains. By simply passing a USER variable of “-froot”, login would accept the “-f” argument, or “treat this user as already logged in”. Instant root!

If this sounds vaguely familiar, it might be because the exact same bug was found in the Solaris telnetd service in 2007, including using the “-f” argument in the USER variable. An extremely similar bug targeting other variables (LD_PRELOAD) was found in the FreeBSD telnetd service in 2009, and other historical similar bugs have afflicted AIX and other Unix systems in the past.

Of course, nobody in 2026 should be running a telnet service, especially not exposed to the Internet, but it’s always interesting to see the old style of bugs resurface.

Glibc

Also reported on the OpenWall list, glibc — the GNU LibC library which underpins most binaries on Linux systems, providing kernel interfaces, file and network I/O, string manipulation, and most other common functions programmers expect — has killed another historical bug, present since 1996 in the DNS resolver functions which could be used to expose some locations in the stack.

Although not exploitable directly, the getnetbyaddr resolution functions could still ease in breaking ASLR, making other exploits viable.

Address Space Layout Randomization (ASLR) is a common method of randomizing where in memory a process and its data are loaded, making trivial exploits like buffer overflows much harder to execute. Being able to expose the location of the binary in memory by leaking stack locations weakens this mechanism, possibly exposing a vulnerable program to more traditional attacks.

MSHTML

In February, Microsoft released fixes under CVE-2026-21513 for the MSHTML Trident renderer – the one used in Internet Explorer 5. Apparently still present in Windows, and somehow still accessible through specific shortcut links, it’s the IE5 and Active-X gift that keeps giving, being actively exploited.

Continue reading “This Week In Security: Getting Back Up To Speed” →

This Week In Security: PostHog, Project Zero Refresh, And Thanks For All The Fish

December 19, 2025 by 18 Comments

There’s something immensely satisfying about taking a series of low impact CVEs, and stringing them together into a full exploit. That’s the story we have from [Mehmet Ince] of Prodraft, who found a handful of issues in the default PostHog install instructions, and managed to turn it into a full RCE, though only accessible as a user with some configuration permissions.

As one might expect, it all starts with a Server Side Request Forgery (SSRF). That’s a flaw where sending traffic to a server can manipulate something on the server side to send a request somewhere else. The trick here is that a webhook worker can be primed to point at localhost by sending a request directly to a system API.

One of the systems that powers a PostHog install is the Clickhouse database server. This project had a problem in how it sanitized SQL requests, namely attempting to escape a single quote via a backslash symbol. In many SQL servers, a backslash would properly escape a single quote, but Clickhouse and other Postgresql servers don’t support that, and treat a backslash as a regular character. And with this, a read-only SQL API is vulnerable to SQL injection.

These vulnerabilities together just allow for injecting an SQL string to create and run a shell command from within the database, giving an RCE and remote shell. The vulnerabilities were reported through ZDI, and things were fixed earlier this year. Continue reading “This Week In Security: PostHog, Project Zero Refresh, And Thanks For All The Fish” →

This Week In Security: Hornet, Gogs, And Blinkenlights

December 12, 2025 by 12 Comments

Microsoft has published a patch-set for the Linux kernel, proposing the Hornet Linux Security Module (LSM). If you haven’t been keeping up with the kernel contributor scoreboard, Microsoft is #11 at time of writing and that might surprise you. The reality is that Microsoft’s biggest source of revenue is their cloud offering, and Azure is over half Linux, so Microsoft really is incentivized to make Linux better.

The Hornet LSM is all about more secure eBPF programs, which requires another aside: What is eBPF? First implemented in the Berkeley Packet Filter, it’s a virtual machine in the kernel, that allows executing programs in kernel space. It was quickly realized that this ability to run a script in kernel space was useful for far more than just filtering packets, and the extended Berkeley Packet Filter was born. eBPF is now used for load balancing, system auditing, security and intrusion detection, and lots more.

This unique ability to load scripts from user space into kernel space has made eBPF useful for malware and spyware applications, too. There is already a signature scheme to restrict eBPF programs, but Hornet allows for stricter checks and auditing. The patch is considered a Request For Comments (RFC), and points out that this existing protection may be subject to Time Of Check / Time Of Use (TOCTOU) attacks. It remains to be seen whether Hornet passes muster and lands in the upstream kernel. Continue reading “This Week In Security: Hornet, Gogs, And Blinkenlights” →

This Week In Security: React, JSON Formatting, And The Return Of Shai Hulud

December 5, 2025 by 3 Comments

After a week away recovering from too much turkey and sweet potato casserole, we’re back for more security news! And if you need something to shake you out of that turkey-induced coma, React Server has a single request Remote Code Execution flaw in versions 19.0.1, 19.1.2, and 19.2.1.

The issue is insecure deserialization in the Flight protocol, as implemented right in React Server, and notably also used in Next.js. Those two organizations have both issued Security Advisories for CVSS 10.0 CVEs.

There are reports of a public Proof of Concept (PoC), but the repository that has been linked explicitly calls out that it is not a true PoC, but merely research into how the vulnerability might work. As far as I can tell, there is not yet a public PoC, but reputable researchers have been able to reverse engineer the problem. This implies that mass exploitation attempts are not far off, if they haven’t already started. Continue reading “This Week In Security: React, JSON Formatting, And The Return Of Shai Hulud” →

This Week In Security: Cloudflare Wasn’t DNS, BADAUDIO, And Not A Vuln

November 21, 2025 by 8 Comments

You may have noticed that large pieces of the Internet were down on Tuesday. It was a problem at Cloudflare, and for once, it wasn’t DNS. This time it was database management, combined with a safety limit that failed unsafe when exceeded.

Cloudflare’s blog post on the matter has the gritty details. It started with an update to how Cloudflare’s ClickHouse distributed database was responding to queries. A query of system columns was previously only returning data from the default database. As a part of related work, that system was changed so that this query now returned all the databases the given user had access to. In retrospect it seems obvious that this could cause problems, but it wasn’t predicted to cause problems. The result was that a database query to look up bot-management features returned the same features multiple times.

That featurelist is used to feed the Cloudflare bot classification system. That system uses some AI smarts, and runs in the core proxy system. There are actually two versions of the core proxy, and they behaved a bit differently when the featurelist exceeded the 200 item limit. When the older version failed, it classified all traffic as a bot. The real trouble was the newer Rust code. That version of the core proxy threw an error in response, leading to 5XX HTTP errors, and the Internet-wide fallout. Continue reading “This Week In Security: Cloudflare Wasn’t DNS, BADAUDIO, And Not A Vuln” →

This Week In Security: Landfall, Imunify AV, And Sudo Rust

November 14, 2025 by 7 Comments

Let’s talk about LANDFALL. That was an Android spyware campaign specifically targeted at Samsung devices. The discovery story is interesting, and possibly an important clue to understanding this particular bit of commercial malware. Earlier this year Apple’s iOS was patched for a flaw in the handling of DNG (Digital NeGative) images, and WhatsApp issued an advisory with a second iOS vulnerability, that together may have been used in attacks in the wild.

Researchers at Unit 42 went looking for real-world examples of this iOS threat campaign, and instead found DNG images that exploited a similar-yet-distinct vulnerability in a Samsung image handling library. These images had a zip file appended to the end of these malicious DNG files. The attack seems to be launched via WhatsApp messaging, just like the iOS attack. That .zip contains a pair of .so shared object files, that are loaded to manipulate the system’s SELinux protections and install the long term spyware payload.

The earliest known sample of this spyware dates to July of 2024, and Samsung patched the DNG handling vulnerability in April 2025. Apple patched the similar DNG problem in August of 2025. The timing and similarities do suggest that these two spyware campaigns may have been related. Unit 42 has a brief accounting of the known threat actors that could have been behind LANDFALL, and concludes that there just isn’t enough solid evidence to make a determination.

Not as Bad as it Looks

Watchtowr is back with a couple more of their unique vulnerability write-ups. The first is a real tease, as they found a way to leak a healthy chunk of memory from Citrix NetScaler machines. The catch is that the memory leak is a part of an error message, complaining that user authentication is disabled. This configuration is already not appropriate for deployment, and the memory leak wasn’t assigned a CVE.

There was a second issue in the NetScaler system, an open redirect in the login system. This is where an attacker can craft a malicious link that points to a trusted NetScaler machine, and if a user follows the link, the NetScaler will redirect the user to a location specified in the malicious link. It’s not a high severity vulnerability, but still got a CVE and a fix. Continue reading “This Week In Security: Landfall, Imunify AV, And Sudo Rust” →

This Week In Security: Bogus Ransom, WordPress Plugins, And KASLR

November 7, 2025 by 16 Comments

There’s another ransomware story this week, but this one comes with a special twist. If you’ve followed this column for long, you’re aware that ransomware has evolved beyond just encrypting files. Perhaps we owe a tiny bit of gratitude to ransomware gangs for convincing everyone that backups are important. The downside to companies getting their backups in order is that these criminals are turning to other means to extort payment from victims. Namely, exfiltrating files and releasing them to the public if the victim doesn’t pay up. And this is the situation in which the Akira ransomware actors claim to have Apache’s OpenOffice project.

There’s just one catch. Akira is threatening to release 23 GB of stolen documents, which include employee information — and the Apache Software Foundation says those documents don’t exist. OpenOffice hasn’t received a demand and can’t find any evidence of a breach. It seems likely that Akira has hit some company, but not part of the Apache Software Foundation. Possibly someone that heavily uses OpenOffice, or even provides some level of support for that application. There is one more wrinkle here.

Since Apache OpenOffice is an open source software project, none of our contributors are paid employees for the project or the foundation…

Continue reading “This Week In Security: Bogus Ransom, WordPress Plugins, And KASLR” →