Vulnerability Name:

CVE-2021-4095 (CCN-215265)

Assigned:2021-12-14
Published:2021-12-14
Updated:2022-07-28
Summary:A NULL pointer dereference was found in the Linux kernel's KVM when dirty ring logging is enabled without an active vCPU context. An unprivileged local attacker on the host may use this flaw to cause a kernel oops condition and thus a denial of service by issuing a KVM_XEN_HVM_SET_ATTR ioctl. This flaw affects Linux kernel versions prior to 5.17-rc1.
CVSS v3 Severity:5.5 Medium (CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
4.8 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
5.5 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
4.8 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
CVSS v2 Severity:1.9 Low (CVSS v2 Vector: AV:L/AC:M/Au:N/C:N/I:N/A:P)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Medium
Authentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Partial
4.6 Medium (CCN CVSS v2 Vector: AV:L/AC:L/Au:S/C:N/I:N/A:C)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Low
Athentication (Au): Single_Instance
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Complete
Vulnerability Type:CWE-476
Vulnerability Consequences:Denial of Service
References:Source: MITRE
Type: CNA
CVE-2021-4095

Source: MLIST
Type: Exploit, Mailing List, Patch, Third Party Advisory
[oss-security] 20220117 Re: CVE-2021-4095: kernel: KVM: NULL pointer dereference in kvm_dirty_ring_get() in virt/kvm/dirty_ring.c

Source: MISC
Type: Exploit, Issue Tracking, Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2031194

Source: XF
Type: UNKNOWN
linux-kernel-cve20214095-dos(215265)

Source: CCN
Type: Linux Kernel GIT Repository
KVM: x86: Fix wall clock writes in Xen shared_info not to mark page dirty

Source: FEDORA
Type: Mailing List, Third Party Advisory
FEDORA-2022-0816754490

Source: FEDORA
Type: Mailing List, Third Party Advisory
FEDORA-2022-8efcea6e67

Source: CCN
Type: oss-sec Mailing List, Tue, 14 Dec 2021 23:26:10 +0800
CVE-2021-4095: kernel: KVM: NULL pointer dereference in kvm_dirty_ring_get() in virt/kvm/dirty_ring.c

Source: CCN
Type: oss-sec Mailing List, Mon, 17 Jan 2022 12:33:54 +0800
Re: CVE-2021-4095: kernel: KVM: NULL pointer dereference in kvm_dirty_ring_get() in virt/kvm/dirty_ring.c

Source: CCN
Type: Linux Kernel Web site
The Linux Kernel Archives

Vulnerable Configuration:Configuration 1:
  • cpe:/o:linux:linux_kernel:*:*:*:*:*:*:*:* (Version <= 5.16)

    • Configuration 2:
  • cpe:/o:fedoraproject:fedora:34:*:*:*:*:*:*:*
  • OR cpe:/o:fedoraproject:fedora:35:*:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    BACK
    linux linux kernel *
    fedoraproject fedora 34
    fedoraproject fedora 35