In plain words
Imagine you have a box where you store things, but the box has a limited size. If someone sends you too many things to put in the box, it will overflow. This is similar to what happens in a stack-based buffer overflow vulnerability¹, where an attacker sends too much data to a program, causing it to overflow and potentially allowing the attacker to run malicious code. A buffer² is like a temporary storage space for data, and a stack³ is a way that programs store and retrieve data in a specific order.
What's broken
The bug is in the GNU libextractor library, specifically in the OLE2 plugin, for versions before 1.15. It has been assigned the identifier CVE-2026-91752⁴. An attacker can craft malicious data to exploit this vulnerability, potentially allowing them to run their own code on the affected system.
How it actually works
The vulnerability works by exploiting a function called `process_star_office` that uses data from an OLE2 stream to size a variable-length stack array. If an attacker can control this data, they can cause the stack array to be too large, leading to a stack-based buffer overflow⁵. This can allow the attacker to execute their own code on the system, potentially leading to a privilege escalation⁶, where the attacker gains more control over the system than they should have.
Proof of concept
There is a public proof-of-concept, or PoC⁷, that demonstrates the vulnerability is real and can be exploited. A PoC is like a test that shows a bug is not just theoretical, but can actually be used to attack a system. This raises the urgency to fix the bug, because it shows that attackers can use it. The PoC shows that the flaw is real and reachable, not just theoretical.
Is it real
It is not clear from the source if this vulnerability is being actively exploited in the wild. However, the fact that a PoC exists makes it more likely that attackers will try to use it. The vulnerability can be fixed by updating GNU libextractor to version 1.15 or later.
What to do
To fix this bug, you should update GNU libextractor to version 1.15 or later. This will prevent attackers from exploiting the vulnerability. If you are using a version prior to 1.15, you should update as soon as possible to protect your system.
Terms
- ¹ stack-based buffer overflow
- , a type of vulnerability that occurs when a program writes more data to a buffer than it can hold
- ² buffer
- , a temporary storage space for data
- ³ stack
- , a way that programs store and retrieve data in a specific order
- ⁴ CVE
- , a unique identifier assigned to a vulnerability
- ⁵ stack-based buffer overflow
- , a type of vulnerability that occurs when a program writes more data to a buffer than it can hold
- ⁶ privilege escalation
- , when an attacker gains more control over a system than they should have
- ⁷ PoC
- , a test that shows a bug is not just theoretical, but can actually be used to attack a system