CVE-2021-23133 | Linux Kernel sctp_destroy_sock race condition

Exp

A race condition in Linux kernel SCTP sockets (net/sctp/socket.c) before 5.12-rc8 can lead to kernel privilege escalation from the context of a network service or an unprivileged process. If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock then an element is removed from the auto_asconf_splist list without any proper locking. This can be exploited by an attacker with network service privileges to escalate to root or from the context of an unprivileged user directly if a BPF_CGROUP_INET_SOCK_CREATE is attached which denies creation of some SCTP socket.

Published: 2021-04-22 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-23133 is rated Exploit Available (55.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.48%). 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-2021-23133

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

Exploit prediction scoring system (EPSS) score for CVE-2021-23133

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 2026-06-15 0.08% 0.48% +0.40%
2 2025-11-21 0.05% 0.08% +0.04%
3 2025-11-18 — 0.05% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-23133

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.7 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.8 5.9 [email protected]
7.0 3.1 HIGH
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.0 5.9 [email protected]
6.9 2.0 MEDIUM
AV:L/AC:M/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.4 10.0 [email protected]

Weakness enumeration for CVE-2021-23133

OS Trackers for CVE-2021-23133

vendor priority summary link
debian not yet assigned CVE-2021-23133 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-2021-23133
redhat medium — https://access.redhat.com/security/cve/CVE-2021-23133
suse high CVE-2021-23133 severity important: SUSE including 431 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 961 product×package rows across 87 product lines (HPE Helion OpenStack 8, Image SLES12-SP5-Azure-BYOS, … (87 product lines)): Fixed 667, Known Affected 187, Known Not Affected 107. https://www.suse.com/security/cve/CVE-2021-23133/
ubuntu medium CVE-2021-23133 medium priority: Ubuntu including 165 source packages (linux, linux-allwinner, …), 2129 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1652, not-affected 222, released 217, ignored 38. https://ubuntu.com/security/CVE-2021-23133

Affected software / configurations for CVE-2021-23133

Vendor Product Version Raw CPE
linux linux_kernel >= 4.10, < 4.14.232 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 4.15, < 4.19.189 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 4.20, < 5.4.114 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.5, < 5.10.32 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.11.16 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
fedoraproject fedora 32 cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
netapp cloud_backup — cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
netapp solidfire_\&_hci_management_node — cpe:2.3:a:netapp:solidfire_\&_hci_management_node:-:*:*:*:*:*:*:*
broadcom brocade_fabric_operating_system — cpe:2.3:o:broadcom:brocade_fabric_operating_system:-:*:*:*:*:*:*:*
netapp h410c_firmware — cpe:2.3:o:netapp:h410c_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 h300e_firmware — cpe:2.3:o:netapp:h300e_firmware:-:*:*:*:*:*:*:*
netapp h500e_firmware — cpe:2.3:o:netapp:h500e_firmware:-:*:*:*:*:*:*:*
netapp h700e_firmware — cpe:2.3:o:netapp:h700e_firmware:-:*:*:*:*:*:*:*
netapp h410s_firmware — cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
netapp solidfire_baseboard_management_controller_firmware — cpe:2.3:o:netapp:solidfire_baseboard_management_controller_firmware:-:*:*:*:*:*:*:*

References for CVE-2021-23133

URL Tags
http://www.openwall.com/lists/oss-security/2021/05/10/1 Mailing List Patch Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/05/10/2 Mailing List Patch Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/05/10/3 Mailing List Patch Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/05/10/4 Mailing List Patch Third Party Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b166a20b07382b8bc1dcee2a448715c9c2c81b5b Mailing List Patch Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00019.html Mitigation Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00020.html Mitigation Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CUX2CA63453G34C6KYVBLJXJXEARZI2X/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAEQ3H6HKNO6KUCGRZVYSFSAGEUX23JL/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XZASHZVCOFJ4VU2I3BN5W5EPHWJQ7QWX/
https://security.netapp.com/advisory/ntap-20210611-0008/ Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/04/18/2 Exploit Mailing List Patch Third Party Advisory
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