5.5 Medium
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
0.0004 Low
EPSS
Percentile
9.1%
A known cache speculation vulnerability, the Branch History Injection (BHI) or Spectre-BHB, was found in new hw (that are cores Cortex: A57, A72, A76, A77, A78, A78AE, A78C, A710, X1, X2; Neoverse: N1, N2, V1; Ampere1). Spectre-BHB is similar to Spectre v2, except that malicious code uses the shared branch history (stored in the CPU Branch History Buffer, or BHB) to influence mispredicted branches within the victim’s hardware context. Once that occurs, speculation caused by the mispredicted branches can cause cache allocation. This issue leads to information disclosure.
Disabling unprivileged eBPF effectively mitigates the known attack vectors for exploiting intra-mode branch injections attacks.
The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl.
For the Red Hat Enterprise Linux 7, the eBPF for unprivileged users is always disabled.
For the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command:
The setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw.