CVE-2021-4203

Exp

A use-after-free read flaw was found in sock_getsockopt() in net/core/sock.c due to SO_PEERCRED and SO_PEERGROUPS race with listen() (and connect()) in the Linux kernel. In this flaw, an attacker with a user privileges may crash the system or leak internal kernel information.

Published: 2022-03-25 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-4203 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.07%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-4203

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-4203

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.93% 0.07% -0.86%
2 2025-11-18 0.05% 0.93% +0.87%
3 2025-07-26 — 0.05% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-4203

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.6 5.2 [email protected]
4.9 2.0 MEDIUM
AV:N/AC:M/Au:S/C:P/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 6.8 4.9 [email protected]

Weakness enumeration for CVE-2021-4203

OS Trackers for CVE-2021-4203

vendor priority summary link
debian not yet assigned CVE-2021-4203 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-4203
redhat medium — https://access.redhat.com/security/cve/CVE-2021-4203
suse medium — https://www.suse.com/security/cve/CVE-2021-4203/
ubuntu medium CVE-2021-4203 medium priority: Ubuntu including 167 source packages (linux, linux-allwinner, …), 2101 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1627, released 222, not-affected 199, ignored 53. https://ubuntu.com/security/CVE-2021-4203

Affected software / configurations for CVE-2021-4203

Vendor Product Version Raw CPE
linux linux_kernel < 5.15 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 5.15 cpe:2.3:o:linux:linux_kernel:5.15:-:*:*:*:*:*:*
linux linux_kernel 5.15 cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*
linux linux_kernel 5.15 cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*
linux linux_kernel 5.15 cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp e-series_santricity_os_controller >= 11.0.0, <= 11.70.2 cpe:2.3:a:netapp:e-series_santricity_os_controller:*:*:*:*:*:*:*:*
netapp element_software — cpe:2.3:a:netapp:element_software:-:*:*:*:*:*:*:*
netapp hci_management_node — cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:*
netapp solidfire — cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*
netapp bootstrap_os — cpe:2.3:o:netapp:bootstrap_os:-:*:*:*:*:*:*:*
netapp a700s_firmware — cpe:2.3:o:netapp:a700s_firmware:-:*:*:*:*:*:*:*
netapp h300s_firmware — cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
netapp h500s_firmware — cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*
netapp h700s_firmware — cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
netapp h410s_firmware — cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
netapp h410c_firmware — cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*
oracle communications_cloud_native_core_binding_support_function 22.1.3 cpe:2.3:a:oracle:communications_cloud_native_core_binding_support_function:22.1.3:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_exposure_function 22.1.1 cpe:2.3:a:oracle:communications_cloud_native_core_network_exposure_function:22.1.1:*:*:*:*:*:*:*
oracle communications_cloud_native_core_policy 22.2.0 cpe:2.3:a:oracle:communications_cloud_native_core_policy:22.2.0:*:*:*:*:*:*:*

References for CVE-2021-4203

cvelogic Threat Intelligence