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CVE-2021-44733

25
FAUCET Score

CVE-2021-44733 is a use-after-free vulnerability in the Linux kernel's TEE subsystem (drivers/tee/tee_shm.c), affecting versions up to 5.15.11, including Debian, Fedora, NetApp, and Red Hat distributions. This high-severity flaw (CVSS 7.0) arises from a race condition during shared memory object deallocation, potentially leading to local privilege escalation with high impact on confidentiality, integrity, and availability. While no public exploits, Metasploit modules, or community discussions are currently identified, its presence in the kernel makes it a notable risk.

Impacted Technologies

VendorProductVersion(s)CPE
<= 5.15.11CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.0HIGH

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

Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.0
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.69%
Probability of exploitation in next 30 days
EPSS Percentile
49.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0069 is in the 86th percentile among its peer group of 1,525 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.4 InfoSec Media, 0.1 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (10)

microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 5.15.18.1-1
microsoftpatch availablevia msrc
Product: 18809-16823Fixed in: 5.15.18.1-1
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 5.15.18.1-1
microsoftpatch availablevia msrc
Product: 18909-16820Fixed in: -
microsoftpatch availablevia msrc
Product: cm1 kernel 5.10.89.1-2 on CBL Mariner 1.0Fixed in: -
microsoftpatch availablevia msrc
Product: cbl2 kernel 5.15.18.1-1 on CBL Mariner 2.0Fixed in: 5.15.18.1-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 5.10.89.1-2
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 5.10.89.1-2
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 redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel-0:4.18.0-372.9.1.el8
View patch

Vendor Advisories (3)

microsoft2022-Jan/CVE-2021-44733

CVE-2021-44733

Jan 11, 2022
redhatCVE-2021-44733Moderate

kernel: use-after-free in the TEE subsystem

Dec 14, 2021
microsoft2021-Dec/CVE-2021-44733Important

A use-after-free exists in drivers/tee/tee_shm.c in the TEE subsystem in the Linux kernel through 5.15.11. This occurs because of a race condition in tee_shm_get_from_id during an attempt to free a shared memory object.

Dec 14, 2021

References

github.com / pjlantz/optee-qemu/blob/main/README.md
ExploitThird Party Advisory
git.kernel.org / cgit/linux/kernel/git/torvalds/linux.git/commit
git.kernel.org / pub/scm/linux/kernel/git/torvalds/linux.git/log/drivers/tee/tee_shm.c
Vendor Advisory
lists.debian.org / debian-lts-announce/2022/03/msg00012.html
Mailing ListThird Party Advisory
lore.kernel.org / lkml/20211215092501.1861229-1-jens.wiklander%40linaro.org
security.netapp.com / advisory/ntap-20220114-0003
Third Party Advisory
debian.org / security/2022/dsa-5096
Third Party Advisory