CVE-2021-23133: Linux Kernel sctp_destroy_sock race condition
Noroxi assessment
Priority: Monitor (action score 28/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.47% (FIRST EPSS).
- Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: linux (Debian:12) 5.10.38-1; linux (Debian:9) 4.9.272-1; linux-4.19 (Debian:9) 4.19.194-1~deb9u1.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to linux (Debian:12) 5.10.38-1; linux (Debian:9) 4.9.272-1; linux-4.19 (Debian:9) 4.19.194-1~deb9u1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- BDU:2021-04855
- DLA-2689-1
- DLA-2690-1
- SUSE-SU-2021:1887-1
- SUSE-SU-2021:1891-1
- SUSE-SU-2021:1899-1
- SUSE-SU-2021:1912-1
- SUSE-SU-2021:1913-1
- SUSE-SU-2021:2332-1
- SUSE-SU-2021:2344-1
- SUSE-SU-2021:2361-1
- SUSE-SU-2021:2366-1
- SUSE-SU-2021:2367-1
- SUSE-SU-2021:2377-1
- SUSE-SU-2021:2384-1
- SUSE-SU-2021:2387-1
- SUSE-SU-2021:2421-1
- SUSE-SU-2021:2453-1
- SUSE-SU-2021:2460-1
- SUSE-SU-2021:2577-1
- Published
- Apr 22, 2021
- Updated
- Jul 30, 2026
- EPSS
- 0.4% · 41th percentile
- CWE
- CWE-362
Report tools
Action score
28
Monitor
Low priority for now.
- CVSS
- 28 / 40 · 7.0 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CNA vs NVD score
- NVD
- 7.0
- CNA · palo_alto
- 6.7
- 0.3 point gap
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| linux | linux kernel | cpe:2.3:o:linux:linux_kernel |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| 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 | h410c | cpe:2.3:h:netapp:h410c |
| netapp | h300s firmware | cpe:2.3:o:netapp:h300s_firmware |
| netapp | h300s | cpe:2.3:h:netapp:h300s |
| netapp | h500s firmware | cpe:2.3:o:netapp:h500s_firmware |
| netapp | h500s | cpe:2.3:h:netapp:h500s |
and 12 more
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- broadcom brocade fabric operating systemall versions
- debian debian linux9.0
- fedoraproject fedora32
- fedoraproject fedora33
- fedoraproject fedora34
- linux linux kernel5.5 and later · before 5.10.37
- linux linux kernel5.11 and later · before 5.11.21
- linux linux kernel5.12 and later · before 5.12.4
- linux linux kernelbefore 4.4.269
- linux linux kernel4.5 and later · before 4.9.269
- linux linux kernel4.10 and later · before 4.14.233
- linux linux kernel4.15 and later · before 4.19.191
- linux linux kernel4.20 and later · before 5.4.119
- netapp cloud backupall versions
- netapp h300e firmwareall versions
- netapp h300s firmwareall versions
- netapp h410c firmwareall versions
- netapp h410s firmwareall versions
- netapp h500e firmwareall versions
- netapp h500s firmwareall versions
Versions reported by the vendor
Affected version ranges reported by the assigning authority (palo_alto). Independent of NVD's CPE analysis and usually ahead of it.
Linux Kernel Linux Kernel
- unspecified and later · before 5.12-rc8affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | linux | before 5.10.38-1 | 5.10.38-1 |
| Debian:9 | linux | before 4.9.272-1 | 4.9.272-1 |
| Debian:9 | linux-4.19 | before 4.19.194-1~deb9u1 | 4.19.194-1~deb9u1 |
| SUSE:Linux Enterprise High Availability Extension 12 SP5 | kernel-default | before 4.12.14-122.74.1 | 4.12.14-122.74.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-docs | before 4.12.14-197.92.1 | 4.12.14-197.92.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-obs-build | before 4.12.14-197.92.1 | 4.12.14-197.92.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-source | before 4.12.14-197.92.1 | 4.12.14-197.92.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-syms | before 4.12.14-197.92.1 | 4.12.14-197.92.1 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | kernel-docs | before 4.12.14-150.75.1 | 4.12.14-150.75.1 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | kernel-obs-build | before 4.12.14-150.75.1 | 4.12.14-150.75.1 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | kernel-source | before 4.12.14-150.75.1 | 4.12.14-150.75.1 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | kernel-syms | before 4.12.14-150.75.1 | 4.12.14-150.75.1 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | kernel-vanilla | before 4.12.14-150.75.1 | 4.12.14-150.75.1 |
| SUSE:Linux Enterprise Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_15 | before 12-2.2 | 12-2.2 |
| SUSE:Linux Enterprise Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_16 | before 11-2.2 | 11-2.2 |
| SUSE:Linux Enterprise Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_17 | before 8-2.2 | 8-2.2 |
| SUSE:Linux Enterprise Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_18 | before 7-2.2 | 7-2.2 |
| SUSE:Linux Enterprise Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_19 | before 6-2.2 | 6-2.2 |
| SUSE:Linux Enterprise Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_20 | before 3-2.1 | 3-2.1 |
| SUSE:Linux Enterprise Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_21 | before 1-6.3.1 | 1-6.3.1 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_10 | before 12-2.2 | 12-2.2 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_11 | before 10-2.2 | 10-2.2 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_12 | before 10-2.2 | 10-2.2 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_13 | before 8-2.2 | 8-2.2 |
+63
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV90Now
- CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV89Now
- CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV85Now
Published before and after this one in the same product
- ← EarlierCVE-2021-3506Apr 19, 2021 · An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel in versions before 5.12.0-rc4.28Monitor
- ← EarlierCVE-2021-29155Apr 20, 2021 · An issue was discovered in the Linux kernel through 5.11.x.22Monitor
- Later →CVE-2021-3501May 6, 2021 · A flaw was found in the Linux kernel in versions before 5.12.28Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:linux | 5.10.38-1 · Debian:12 | Package registry (OSV) |
| debian:linux-4.19 | 4.19.194-1~deb9u1 · Debian:9 | Package registry (OSV) |
| suse:kernel-azure | 4.12.14-16.59.1 · SUSE:Linux Enterprise Server 12 SP5 | Package registry (OSV) |
| suse:kernel-default | 4.12.14-95.77.1 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:kernel-livepatch-SLE15-SP1_Update_25 | 1-3.3.1 · SUSE:Linux Enterprise Live Patching 15 SP1 | Package registry (OSV) |
| suse:kernel-rt | 4.12.14-10.46.1 · SUSE:Linux Enterprise Real Time 12 SP5 | Package registry (OSV) |
| suse:kernel-rt_debug | 4.12.14-10.46.1 · SUSE:Linux Enterprise Real Time 12 SP5 | Package registry (OSV) |
| suse:kernel-source | 4.12.14-95.77.1 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:kernel-source-azure | 4.12.14-16.59.1 · SUSE:Linux Enterprise Server 12 SP5 | Package registry (OSV) |
| suse:kernel-source-rt | 4.12.14-10.46.1 · SUSE:Linux Enterprise Real Time 12 SP5 | Package registry (OSV) |
| suse:kernel-syms | 4.12.14-95.77.1 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:kernel-syms-azure | 4.12.14-16.59.1 · SUSE:Linux Enterprise Server 12 SP5 | Package registry (OSV) |
| suse:kernel-syms-rt | 4.12.14-10.46.1 · SUSE:Linux Enterprise Real Time 12 SP5 | Package registry (OSV) |
| suse:kgraft-patch-SLE12-SP4_Update_21 | 1-6.3.1 · SUSE:Linux Enterprise Live Patching 12 SP4 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Or CohenPalo Alto Networks
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-21-0523 · Jun 28, 2021(Ubuntu Güvenlik Bildirimi Yayınladı)
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- High
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')CVSS vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (10 more)Show less
- www.openwall.com/lists/oss-security/2021/05/10/2
- www.openwall.com/lists/oss-security/2021/05/10/3
- www.openwall.com/lists/oss-security/2021/05/10/4
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b166a20b07382b8bc1dcee2a448715c9c2c81b5b
- lists.debian.org/debian-lts-announce/2021/06/msg00019.html
- lists.debian.org/debian-lts-announce/2021/06/msg00020.html
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CUX2CA63453G34C6KYVBLJXJXEARZI2X/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAEQ3H6HKNO6KUCGRZVYSFSAGEUX23JL/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XZASHZVCOFJ4VU2I3BN5W5EPHWJQ7QWX/
- security.netapp.com/advisory/ntap-20210611-0008/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.