CVE-2021-21781 Information disclosure in Linux Kernel

What is CVE-2021-21781?

CVE-2021-21781 is a medium-severity vulnerability in Linux kernel, published on 18 Aug 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

An information disclosure vulnerability exists in the ARM SIGPAGE functionality of Linux Kernel v5.4.66 and v5.4.54. The latest version (5.11-rc4) seems to still be vulnerable. A userland application can read the contents of the sigpage, which can leak kernel memory contents. An attacker can read a process’s memory at a specific offset to trigger this vulnerability. This was fixed in kernel releases: 4.14.222 4.19.177 5.4.99 5.10.17 5.11

Weakness: CWE-908

Which versions are affected by CVE-2021-21781?

It affects 4 products.

Products include Linux kernel, Oracle Communications Cloud Native Core Binding Support Function, Oracle Communications Cloud Native Core Network Exposure Function, Oracle Communications Cloud Native Core Policy.

How do I fix CVE-2021-21781?

Apply the vendor's patch.

Is CVE-2021-21781 being exploited?

There is no known exploitation of CVE-2021-21781 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as A-197850306, DEBIAN-CVE-2021-21781, GHSA-v4c8-84p4-cxv7, PUB-A-197850306, UBUNTU-CVE-2021-21781.