CVE-2020-8835

Linux kernel bpf verifier vulnerability

Published Apr 2, 2020 CVSS 3.1 · 7.8 High EPSS 6.0% KEV · Not listed
Description
In the Linux kernel 5.5.0 and newer, the bpf verifier (kernel/bpf/verifier.c) did not properly restrict the register bounds for 32-bit operations, leading to out-of-bounds reads and writes in kernel memory. The vulnerability also affects the Linux 5.4 stable series, starting with v5.4.7, as the introducing commit was backported to that branch. This vulnerability was fixed in 5.6.1, 5.5.14, and 5.4.29. (issue is aka ZDI-CAN-10780)

Remediation

Vendor Solution

Revert commit 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions").


Vendor Workaround

Mitigation for this vulnerability is available by setting the kernel.unprivileged_bpf_disabled sysctl to 1: $ sudo sysctl kernel.unprivileged_bpf_disabled=1 $ echo kernel.unprivileged_bpf_disabled=1 | sudo tee /etc/sysctl.d/90-CVE-2020-8835.conf This issue is also mitigated on systems that use secure boot with the kernel lockdown feature which blocks BPF program loading.

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-4313-1 Linux kernel vulnerability
History

No history.

Weaknesses

Sources

Status
PUBLISHED
Assigner
canonical
Published
Updated
Sep 17, 2024, 2:15 AM
Reserved
Feb 10, 2020, 12:00 AM
Status
Modified
Published
Apr 2, 2020, 6:15 PM
Modified
Jun 17, 2026, 3:27 AM
Severity
Important
Public date
Mar 30, 2020, 4:00 PM