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CVE-2021-43389

20
FAUCET Score

CVE-2021-43389 describes an array-index-out-of-bounds flaw within the detach_capi_ctr function in the Linux kernel's CAPI driver, affecting versions prior to 5.14.15, including Debian, Oracle, and Red Hat distributions. Rated Medium (CVSS 5.5), this vulnerability can be exploited locally with low complexity, leading to a high impact on availability, though confidentiality and integrity are not directly affected. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.14.15CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:-:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
22.1.3CPE matchmatch criteria
cpe:2.3:a:oracle:communications_cloud_native_core_binding_support_function:22.1.3:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.5MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.67%
Probability of exploitation in next 30 days
EPSS Percentile
48.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0067 is in the 95th percentile among its peer group of 15,940 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (8)

microsoftpatch availablevia msrc
Product: 16885-16820Fixed in: 5.10.78.1-1
microsoftpatch availablevia msrc
Product: cm1 kernel 5.10.78.1-1 on CBL Mariner 1.0Fixed in: 5.10.78.1-1
microsoftpatch availablevia msrc
Product: cbl2 kernel 5.10.78.1-1 on CBL Mariner 2.0Fixed in: 5.10.78.1-1
microsoftpatch availablevia msrc
Product: 16920-16823Fixed in: 5.10.78.1-1
oraclepatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel-rt-0:4.18.0-372.9.1.rt7.166.el8
View patch
redhatpatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel-0:4.18.0-372.9.1.el8
View patch

Vendor Advisories (2)

microsoft2021-Nov/CVE-2021-43389Moderate

An issue was discovered in the Linux kernel before 5.14.15. There is an array-index-out-of-bounds flaw in the detach_capi_ctr function in drivers/isdn/capi/kcapi.c.

Nov 9, 2021
redhatCVE-2021-43389Moderate

kernel: an array-index-out-bounds in detach_capi_ctr in drivers/isdn/capi/kcapi.c

Sep 24, 2021

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingPatchThird Party Advisory
cdn.kernel.org / pub/linux/kernel/v5.x/ChangeLog-5.14.15
Mailing ListRelease NotesThird Party Advisory
git.kernel.org / pub/scm/linux/kernel/git/torvalds/linux.git/commit
Mailing ListPatchThird Party Advisory
lists.debian.org / debian-lts-announce/2021/12/msg00012.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2022/03/msg00012.html
Mailing ListThird Party Advisory
lore.kernel.org / netdev/CAFcO6XOvGQrRTaTkaJ0p3zR7y7nrAWD79r48=L_BbOyrK9X-vA%40mail.gmail.com
seclists.org / oss-sec/2021/q4/39
ExploitMailing ListThird Party Advisory
debian.org / security/2022/dsa-5096
Third Party Advisory
oracle.com / security-alerts/cpujul2022.html
PatchThird Party Advisory
openwall.com / lists/oss-security/2021/11/05/1
Mailing ListThird Party Advisory