Moderate Vulnerability in glibc: Heap Buffer Overflow in scanf
Summary
ALSA-2026:33092: Moderate: glibc security, bug fix, and enhancement update. Affects glibc versions < 2.39-126.el10_2.alma.1. Fixed in 2.39-126.el10_2.alma.1. How to fix ↓
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Background
The glibc (GNU C Library) package provides essential C libraries, including standard math libraries and POSIX thread libraries, crucial for the proper functioning of Linux systems. This library is widely used across various applications, making it a critical component of the operating system. The recent vulnerability identified affects the scanf function when using the %mc format specifier with large width inputs, potentially leading to a heap buffer overflow.
Vulnerability Detail
The vulnerability arises from a heap buffer overflow in the glibc library's scanf function when the %mc format specifier is used with excessively large width values. This flaw can be exploited by attackers to execute arbitrary code, leading to potential system compromise. The vulnerability is documented under CVE-2026-5450, which highlights the risk of memory corruption and unauthorized access to sensitive data.
How To Fix
Minimum fixed version
2.39-126.el10_2.alma.1
This is the first release that contains the fix.
sudo dnf update glibcTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, avoid using the scanf function with the %mc format specifier or limit the width of the input to prevent potential overflow. Consider using safer alternatives for input handling.
Conclusion
The glibc vulnerability CVE-2026-5450 poses a significant risk due to its potential for exploitation through heap buffer overflow. It is crucial for users to update their glibc packages to the patched version to mitigate this risk and ensure system security.
See every vulnerability recorded for glibc →
FAQ
glibc, or GNU C Library, is the standard C library used by many Linux systems, providing essential functions for C programming and system calls.
CVE-2026-5450 refers to a heap buffer overflow vulnerability in the glibc library's scanf function, which can lead to memory corruption and potential system exploitation.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The risks include unauthorized access to system resources, potential data breaches, and the ability for attackers to execute arbitrary code on affected systems.
Yes, Vulert provides a service that monitors and alerts in real-time for open-source vulnerabilities using just a manifest file like package-lock.json.
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