CVE-2021-4001 - OpenCVE

A race condition was found in the Linux kernel's ebpf verifier between bpf_map_update_elem and bpf_map_freeze due to a missing lock in kernel/bpf/syscall.c. In this flaw, a local user with a special privilege (cap_sys_admin or cap_bpf) can modify the frozen mapped address space. This flaw affects kernel versions prior to 5.16 rc2.

No CVSS v4.0

Attack Vector Local

Attack Complexity High

Privileges Required High

Scope Unchanged

Confidentiality Impact None

Integrity Impact High

Availability Impact None

User Interaction None

No CVSS v3.0

Access Vector Local

Access Complexity Medium

Authentication None

Confidentiality Impact None

Integrity Impact Complete

Availability Impact None

AV:L/AC:M/Au:N/C:N/I:C/A:N

This CVE is not in the KEV list.

Key SSVC decision points have not yet been added.

Vendors	Products
Linux	Linux Kernel

Configuration 1 [-]

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:5.16:rc1::::::

No data.

References

Link	Providers
https://bugzilla.redhat.com/show_bug.cgi?id=2025645
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=353050be4c19e102178ccc05988101887c25ae53
https://nvd.nist.gov/vuln/detail/CVE-2021-4001
https://www.cve.org/CVERecord?id=CVE-2021-4001

History

No history.

MITRE

Status: PUBLISHED

Assigner: redhat

Published: 2022-01-21T00:00:00

Updated: 2024-08-03T17:16:03.566Z

Reserved: 2021-11-22T00:00:00

Link: CVE-2021-4001

Vulnrichment

No data.

NVD

Status : Analyzed

Published: 2022-01-21T19:15:09.703

Modified: 2022-11-16T03:36:38.540

Link: CVE-2021-4001

Redhat

Severity : Moderate

Publid Date: 2021-11-15T00:00:00Z

Links: CVE-2021-4001 - Bugzilla

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{"acknowledgement": "Red Hat would like to thank anciety@starcross, swing@chaitin, and w1tcher@w1tcherSun for reporting this issue.", "bugzilla": {"description": "kernel: race condition when the EBPF map is frozen", "id": "2025645", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2025645"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.7", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-367", "details": ["A race condition was found in the Linux kernel's ebpf verifier between bpf_map_update_elem and bpf_map_freeze due to a missing lock in kernel/bpf/syscall.c. In this flaw, a local user with a special privilege (cap_sys_admin or cap_bpf) can modify the frozen mapped address space. This flaw affects kernel versions prior to 5.16 rc2.", "A race condition was found in the Linux kernel's ebpf verifier between bpf_map_update_elem and bpf_map_freeze due to a missing lock in kernel/bpf/syscall.c. In this flaw, a local user with a special privilege (cap_sys_admin or cap_bpf) can modify the frozen mapped address space."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}, "name": "CVE-2021-4001", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "impact": "low", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "impact": "low", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2021-11-15T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-4001\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-4001\nhttps://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=353050be4c19e102178ccc05988101887c25ae53"], "statement": "The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl. This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space.\nFor the Red Hat Enterprise Linux 7 the eBPF for unprivileged users is always disabled.\nFor the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command:\n```\n# cat /proc/sys/kernel/unprivileged_bpf_disabled\n```\nThe setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw.\nA kernel update will be required to mitigate the flaw for the root or users with CAP_SYS_ADMIN capabilities.", "threat_severity": "Moderate", "upstream_fix": "kernel 5.16 rc2"}