This Week in Security

294 Articles

This Week In Security: Linux Flaws, Python Ownage, And A Botnet Shutdown

March 20, 2026 by 12 Comments

The ides of security March are upon us — Qualys reports the discovery by their threat research unit of vulnerabilities in the Linux AppArmor system used by SUSE, Debian, Ubuntu, and Kubernetes as an additional security mechanism and application firewall.

AppArmor was added to Linux in 2010, and the vulnerabilities Qualys discovered have been present since 2017, and allow unprivileged (non-root) local users to elevate privileges by executing arbitrary code in the kernel, gaining root access, or perform a denial-of-service attack across the entire system by replacing all AppArmor behavior with “deny all” rules.

All Linux kernels since Linux 4.11 are vulnerable. If your Linux distribution enables AppArmor, and quite a few do, you’ll want to be updating as soon as fixes are available from your distribution maintainers. On systems with untrusted users, such as shared environments, VPS server environments, and the like, this is even more critical and urgent. Even on single-user systems, vulnerabilities like these allow other exploits, like the Python attack below, mechanisms to elevate their access and persistence.

At the time of writing, the full details of the AppArmor vulnerability are limited until the Linux Kernel team releases a stable version with the fixes for distribution maintainers. Qualys has published the technical write-up with the currently public information.

Python Projects Compromised

StepSecurity reports on a new campaign to infect Python projects on GitHub with a complex malware that, once deployed, appears to be yet another crypto and login stealer.

The attacker first gains access to the GitHub credentials via another info stealing worm – the Glassworm stealer infects VSCode extensions with over 35,000 downloads of infected extensions in October of 2025. Glassworm harvests NPM, GitHub, and OpenVSX credentials and sends them to a remote command and control (C2) server. It also harvests a wide range of crypto currency wallet extensions to steal crypto directly. Continue reading “This Week In Security: Linux Flaws, Python Ownage, And A Botnet Shutdown” →

This Week In Security: Plenty Of Patches, Replacing Old Gear, And Phrack Calls For Papers

March 13, 2026 by 7 Comments

When Friday the Thirteenth and Patch Tuesday happen on the same week, we’re surely in for a good time.

Anyone who maintains any sort of Microsoft ecosystem knows by now to brace for impact come Patch Tuesday; March brings the usual batch of “interesting” issues, including:

  • Two high-risk Microsoft Office vulnerabilities (CVE-2026-26110 and CVE-2026-26113), both of which allow execution of arbitrary code with no user interaction other than opening a hostile file. Vulnerabilities like these are especially dangerous in environments where transferring Office documents is considered normal, such as (unsurprisingly) offices, but also for home users who may not be savvy enough to avoid opening hostile files. Arbitrary code execution allows the attacker to run essentially any commands the user would be able to run themselves, typically leveraging it to install remote access or keyboard logging malware.
  • Excel gets a different vulnerability, CVE-2026-26144, which allows leaking of data through a cross-site scripting vulnerability. Coupled with CoPilot Agent, this can be used to leak contents of spreadsheets, again with no direct user interaction.

On the server and container side, this month includes a fairly typical collection of patches for SQL Server, and vulnerabilities in the Microsoft-hosted device pricing and payment orchestrator services, which have been automatically patched by Microsoft. Continue reading “This Week In Security: Plenty Of Patches, Replacing Old Gear, And Phrack Calls For Papers” →

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” →