#VU51774 Observable discrepancy in Linux kernel - CVE-2020-27170

Vulnerability identifier: #VU51774

Vulnerability risk: Low

CVSSv4.0: 4.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-27170

CWE-ID: CWE-203

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists in kernel/bpf/verifier.c due to kernel performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations. A local user can run a specially crafted program to gain access to sensitive information.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.11.8, 5.11.8

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External links
https://www.openwall.com/lists/oss-security/2021/03/24/4
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.8
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f232326f6966cf2a1d1db7bc917a4ce5f9f55f76
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FB6LUXPEIRLZH32YXWZVEZAD4ZL6SDK2/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QRTPQE73ANG7D6M4L4PK5ZQDPO4Y2FVD/
https://www.openwall.com/lists/oss-security/2021/03/19/2

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.