Red Hat Enterprise Linux 7 update for kernel



Published: 2021-10-13
Risk Medium
Patch available YES
Number of vulnerabilities 4
CVE-ID CVE-2021-22543
CVE-2021-3653
CVE-2021-3656
CVE-2021-37576
CWE-ID CWE-119
CWE-264
CWE-787
Exploitation vector Network
Public exploit Public exploit code for vulnerability #1 is available.
Vulnerable software
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kernel (Red Hat package)
Operating systems & Components / Operating system package or component

Red Hat Enterprise Linux for Power, little endian
Operating systems & Components / Operating system

Red Hat Enterprise Linux for Power, big endian
Operating systems & Components / Operating system

Red Hat Enterprise Linux for IBM z Systems
Operating systems & Components / Operating system

Red Hat Enterprise Linux for Scientific Computing
Operating systems & Components / Operating system

Red Hat Enterprise Linux Desktop
Operating systems & Components / Operating system

Red Hat Enterprise Linux Workstation
Operating systems & Components / Operating system

Red Hat Enterprise Linux Server
Operating systems & Components / Operating system

Vendor Red Hat Inc.

Security Bulletin

This security bulletin contains information about 4 vulnerabilities.

1) Buffer overflow

EUVDB-ID: #VU56018

Risk: Low

CVSSv3.1: 7 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2021-22543

CWE-ID: CWE-119 - Improper Restriction of Operations within the Bounds of a Memory Buffer

Exploit availability: Yes

Description

The 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.


Mitigation

Install updates from vendor's website.

Vulnerable software versions

kernel (Red Hat package): 3.10.0-1160.6.1.el7, 3.10.0-1160.11.1.el7, 3.10.0-1160.21.1.el7, 3.10.0-1160.24.1.el7, 3.10.0-1160.31.1.el7, 3.10.0-1160.36.2.el7, 3.10.0-1160.41.1.el7, 3.10.0-1160.42.2.el7

Red Hat Enterprise Linux for Power, little endian: 7

Red Hat Enterprise Linux for Power, big endian: 7

Red Hat Enterprise Linux for IBM z Systems: 7

Red Hat Enterprise Linux for Scientific Computing: 7

Red Hat Enterprise Linux Desktop: 7

Red Hat Enterprise Linux Workstation: 7

Red Hat Enterprise Linux Server: 7

CPE2.3 External links

http://access.redhat.com/errata/RHSA-2021:3801

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.

2) Security restrictions bypass

EUVDB-ID: #VU56904

Risk: Low

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-3653

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The 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.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

kernel (Red Hat package): 3.10.0-1160.6.1.el7, 3.10.0-1160.11.1.el7, 3.10.0-1160.21.1.el7, 3.10.0-1160.24.1.el7, 3.10.0-1160.31.1.el7, 3.10.0-1160.36.2.el7, 3.10.0-1160.41.1.el7, 3.10.0-1160.42.2.el7

Red Hat Enterprise Linux for Power, little endian: 7

Red Hat Enterprise Linux for Power, big endian: 7

Red Hat Enterprise Linux for IBM z Systems: 7

Red Hat Enterprise Linux for Scientific Computing: 7

Red Hat Enterprise Linux Desktop: 7

Red Hat Enterprise Linux Workstation: 7

Red Hat Enterprise Linux Server: 7

CPE2.3 External links

http://access.redhat.com/errata/RHSA-2021:3801

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.

3) Security restrictions bypass

EUVDB-ID: #VU56929

Risk: Low

CVSSv3.1: 6.8 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-3656

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The 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.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

kernel (Red Hat package): 3.10.0-1160.6.1.el7, 3.10.0-1160.11.1.el7, 3.10.0-1160.21.1.el7, 3.10.0-1160.24.1.el7, 3.10.0-1160.31.1.el7, 3.10.0-1160.36.2.el7, 3.10.0-1160.41.1.el7, 3.10.0-1160.42.2.el7

Red Hat Enterprise Linux for Power, little endian: 7

Red Hat Enterprise Linux for Power, big endian: 7

Red Hat Enterprise Linux for IBM z Systems: 7

Red Hat Enterprise Linux for Scientific Computing: 7

Red Hat Enterprise Linux Desktop: 7

Red Hat Enterprise Linux Workstation: 7

Red Hat Enterprise Linux Server: 7

CPE2.3 External links

http://access.redhat.com/errata/RHSA-2021:3801

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.

4) Out-of-bounds write

EUVDB-ID: #VU57101

Risk: Medium

CVSSv3.1: 7 [CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-37576

CWE-ID: CWE-787 - Out-of-bounds Write

Exploit availability: No

Description

The 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.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

kernel (Red Hat package): 3.10.0-1160.6.1.el7, 3.10.0-1160.11.1.el7, 3.10.0-1160.21.1.el7, 3.10.0-1160.24.1.el7, 3.10.0-1160.31.1.el7, 3.10.0-1160.36.2.el7, 3.10.0-1160.41.1.el7, 3.10.0-1160.42.2.el7

Red Hat Enterprise Linux for Power, little endian: 7

Red Hat Enterprise Linux for Power, big endian: 7

Red Hat Enterprise Linux for IBM z Systems: 7

Red Hat Enterprise Linux for Scientific Computing: 7

Red Hat Enterprise Linux Desktop: 7

Red Hat Enterprise Linux Workstation: 7

Red Hat Enterprise Linux Server: 7

CPE2.3 External links

http://access.redhat.com/errata/RHSA-2021:3801

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.



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