Linux Kernel up to 5.7.1 keyboard.c k_ascii integer overflow

Summaryinfo

A vulnerability was found in Linux Kernel up to 5.7.1 and classified as critical. This impacts the function k_ascii of the file drivers/tty/vt/keyboard.c. Such manipulation leads to integer overflow. This vulnerability is referenced as CVE-2020-13974. The attack can only be performed from a local environment. No exploit is available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 5.7.1 (Operating System). Affected by this issue is the function k_ascii of the file drivers/tty/vt/keyboard.c. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is confidentiality, integrity, and availability. CVE summarizes:

An issue was discovered in the Linux kernel through 5.7.1. drivers/tty/vt/keyboard.c has an integer overflow if k_ascii is called several times in a row, aka CID-b86dab054059.

The weakness was published 06/09/2020. This vulnerability is handled as CVE-2020-13974 since 06/09/2020. The attack needs to be approached locally. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 06/20/2025).

The vulnerability scanner Nessus provides a plugin with the ID 239841 (TencentOS Server 4: kernel (TSSA-2024:0960)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (239841). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.7.0
• 5.7.1

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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