Red Hat Enterprise Linux 7 update for kernel
| Risk | Medium |
| Patch available | YES |
| Number of vulnerabilities | 6 |
| CVE-ID | CVE-2019-20934 CVE-2020-36385 CVE-2021-22543 CVE-2021-3653 CVE-2021-3656 CVE-2021-37576 |
| CWE-ID | CWE-416 CWE-119 CWE-264 CWE-787 |
| Exploitation vector | Network |
| Public exploit | Public exploit code for vulnerability #3 is available. |
| Vulnerable software |
Red Hat Enterprise Linux Server - TUS Operating systems & Components / Operating system Red Hat Enterprise Linux Server - AUS Operating systems & Components / Operating system kernel (Red Hat package) Operating systems & Components / Operating system package or component |
| Vendor | Red Hat Inc. |
Security Bulletin
This security bulletin contains information about 6 vulnerabilities.
1) Use-after-free
EUVDB-ID: #VU55260
Risk: Low
CVSSv4.0: 2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]
CVE-ID: CVE-2019-20934
CWE-ID:
CWE-416 - Use After Free
Exploit availability: No
DescriptionThe vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a use-after-free error in Linux fair scheduler within the show_numa_stats() function, caused by improperly freed NUMA fault statistics. A local user can trigger a use-after-free error and escalate privileges on the system.
Install updates from vendor's website.
Red Hat Enterprise Linux Server - TUS: 7.7
Red Hat Enterprise Linux Server - AUS: 7.7
kernel (Red Hat package): before 3.10.0-1062.59.1.el7
CPE2.3- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_tus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_aus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:kernel_redhat_package:*:*:*:*:*:red_hat_enterprise_linux:*:*
https://access.redhat.com/errata/RHSA-2021:3987
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.
2) Use-after-free
EUVDB-ID: #VU58332
Risk: Low
CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]
CVE-ID: CVE-2020-36385
CWE-ID:
CWE-416 - Use After Free
Exploit availability: No
DescriptionThe vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a use-after-free error in drivers/infiniband/core/ucma.c, because the ctx is reached via the ctx_list in some ucma_migrate_id situations where ucma_close is called. A local user can run a specially crafted program to trigger the use-after-free error and execute arbitrary code with elevated privileges.
Install updates from vendor's website.
Red Hat Enterprise Linux Server - TUS: 7.7
Red Hat Enterprise Linux Server - AUS: 7.7
kernel (Red Hat package): before 3.10.0-1062.59.1.el7
CPE2.3- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_tus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_aus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:kernel_redhat_package:*:*:*:*:*:red_hat_enterprise_linux:*:*
https://access.redhat.com/errata/RHSA-2021:3987
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.
3) Buffer overflow
EUVDB-ID: #VU56018
Risk: Low
CVSSv4.0: 7.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Clear]
CVE-ID: CVE-2021-22543
CWE-ID:
CWE-119 - Memory corruption
Exploit availability: Yes
DescriptionThe vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a boundary error in Linux kernel when handling VM_IO|VM_PFNMAP vmas in KVM. A local user can can bypass RO checks and cause the pages to get freed while still accessible by the VMM and guest. As a result, an attacker with the ability to start and control a VM to read/write random pages of memory, can trigger memory corruption and execute arbitrary code with elevated privileges.
Install updates from vendor's website.
Red Hat Enterprise Linux Server - TUS: 7.7
Red Hat Enterprise Linux Server - AUS: 7.7
kernel (Red Hat package): before 3.10.0-1062.59.1.el7
CPE2.3- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_tus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_aus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:kernel_redhat_package:*:*:*:*:*:red_hat_enterprise_linux:*:*
https://access.redhat.com/errata/RHSA-2021:3987
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. However, proof of concept for this vulnerability is available.
4) Security restrictions bypass
EUVDB-ID: #VU56904
Risk: Low
CVSSv4.0: 5.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]
CVE-ID: CVE-2021-3653
CWE-ID:
CWE-264 - Permissions, Privileges, and Access Controls
Exploit availability: No
DescriptionThe vulnerability allows a malicious guest to escalate privileges on the system.
The vulnerability exists due to improperly imposed security restrictions within the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "int_ctl" field, this issue could allow a malicious L1 to enable AVIC support (Advanced Virtual Interrupt Controller) for the L2 guest.
As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape.
Install updates from vendor's website.
Red Hat Enterprise Linux Server - TUS: 7.7
Red Hat Enterprise Linux Server - AUS: 7.7
kernel (Red Hat package): before 3.10.0-1062.59.1.el7
CPE2.3- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_tus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_aus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:kernel_redhat_package:*:*:*:*:*:red_hat_enterprise_linux:*:*
https://access.redhat.com/errata/RHSA-2021:3987
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
5) Security restrictions bypass
EUVDB-ID: #VU56929
Risk: Low
CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]
CVE-ID: CVE-2021-3656
CWE-ID:
CWE-264 - Permissions, Privileges, and Access Controls
Exploit availability: No
DescriptionThe vulnerability allows a malicious guest to escalate privileges on the system.
The vulnerability exists due to improperly imposed security restrictions within the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "virt_ext" field, this issue could allow a malicious L1 to disable both VMLOAD/VMSAVE intercepts and VLS (Virtual VMLOAD/VMSAVE) for the L2 guest.The vulnerability allows the L2 guest to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape.
Install updates from vendor's website.
Red Hat Enterprise Linux Server - TUS: 7.7
Red Hat Enterprise Linux Server - AUS: 7.7
kernel (Red Hat package): before 3.10.0-1062.59.1.el7
CPE2.3- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_tus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_aus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:kernel_redhat_package:*:*:*:*:*:red_hat_enterprise_linux:*:*
https://access.redhat.com/errata/RHSA-2021:3987
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.
6) Out-of-bounds write
EUVDB-ID: #VU57101
Risk: Medium
CVSSv4.0: 4.8 [CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]
CVE-ID: CVE-2021-37576
CWE-ID:
CWE-787 - Out-of-bounds write
Exploit availability: No
DescriptionThe vulnerability allows a remote user to escalate privileges on the system.
The vulnerability exists due to a boundary error in arch/powerpc/kvm/book3s_rtas.c in the Linux kernel through 5.13.5 on the powerpc platform. An attacker on KVM guest OS can cause host OS memory corruption via rtas_args.nargs and execute arbitrary code on the host OS.
Install updates from vendor's website.
Red Hat Enterprise Linux Server - TUS: 7.7
Red Hat Enterprise Linux Server - AUS: 7.7
kernel (Red Hat package): before 3.10.0-1062.59.1.el7
CPE2.3- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_tus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:red_hat_enterprise_linux_server_-_aus:7.7:*:*:*:*:red_hat_enterprise_linux:*:*
- cpe:2.3:o:red_hat:kernel_redhat_package:*:*:*:*:*:red_hat_enterprise_linux:*:*
https://access.redhat.com/errata/RHSA-2021:3987
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated privileged user via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
