NVD / CVE Program· CNA mitre

CVE-2021-3347: An issue was discovered in the Linux kernel through 5.10.11.

Noroxi assessment

Priority: Monitor (action score 31/100)

Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
Probability of exploitation in the next 30 days: 1.3% (FIRST EPSS); higher than 71.7% of all records.
Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: kernel-abi-whitelists (AlmaLinux:8) 4.18.0-240.22.1.el8_3; kernel-tools-libs-devel (AlmaLinux:8) 4.18.0-240.22.1.el8_3; linux (Debian:10) 4.19.171-2.
Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to kernel-abi-whitelists (AlmaLinux:8) 4.18.0-240.22.1.el8_3; kernel-tools-libs-devel (AlmaLinux:8) 4.18.0-240.22.1.el8_3; linux (Debian:10) 4.19.171-2 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

An issue was discovered in the Linux kernel through 5.10.11. PI futexes have a kernel stack use-after-free during fault handling, allowing local users to execute code in the kernel, aka CID-34b1a1ce1458.

HighCVSS 7.8 · v3.1—Proof of concept Fix available

Memory safety

Published: Jan 29, 2021
Updated: Jun 17, 2026
EPSS: 1.3% · 71th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 1.3%

CISA SSVC decision

Exploitation: proof of concept
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
Proof of concept exists, no weaponized module
A fix has been released

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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.

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Affected 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
debian	debian linux	cpe:2.3:o:debian:debian_linux
fedoraproject	fedora	cpe:2.3:o:fedoraproject:fedora

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

debian debian linux10.0
debian debian linux9.0
fedoraproject fedora32
fedoraproject fedora33
linux linux kernelup to 5.10.11 inclusive

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
AlmaLinux:8	kernel-abi-whitelists	before 4.18.0-240.22.1.el8_3	4.18.0-240.22.1.el8_3
AlmaLinux:8	kernel-tools-libs-devel	before 4.18.0-240.22.1.el8_3	4.18.0-240.22.1.el8_3
Debian:10	linux	before 4.19.171-2	4.19.171-2
Debian:12	linux	before 5.10.12-1	5.10.12-1
Debian:9	linux	before 4.9.258-1	4.9.258-1
Debian:9	linux-4.19	before 4.19.171-2~deb9u1	4.19.171-2~deb9u1
openSUSE:Leap 15.2	kernel-debug	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
openSUSE:Leap 15.2	kernel-default	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
openSUSE:Leap 15.2	kernel-default-base	before 5.3.18-lp152.63.1.lp152.8.21.1	5.3.18-lp152.63.1.lp152.8.21.1
openSUSE:Leap 15.2	kernel-docs	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
openSUSE:Leap 15.2	kernel-kvmsmall	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
openSUSE:Leap 15.2	kernel-obs-build	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
openSUSE:Leap 15.2	kernel-obs-qa	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
openSUSE:Leap 15.2	kernel-preempt	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
openSUSE:Leap 15.2	kernel-source	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
openSUSE:Leap 15.2	kernel-syms	before 5.3.18-lp152.63.1	5.3.18-lp152.63.1
Red Hat:enterprise_linux:7::client	bpftool	before 0:3.10.0-1160.31.1.el7	0:3.10.0-1160.31.1.el7
Red Hat:enterprise_linux:7::client	bpftool-debuginfo	before 0:3.10.0-1160.31.1.el7	0:3.10.0-1160.31.1.el7
Red Hat:enterprise_linux:7::client	kernel	before 0:3.10.0-1160.31.1.el7	0:3.10.0-1160.31.1.el7
Red Hat:enterprise_linux:7::client	kernel-abi-whitelists	before 0:3.10.0-1160.31.1.el7	0:3.10.0-1160.31.1.el7
Red Hat:enterprise_linux:7::client	kernel-debug	before 0:3.10.0-1160.31.1.el7	0:3.10.0-1160.31.1.el7
Red Hat:enterprise_linux:7::client	kernel-debug-debuginfo	before 0:3.10.0-1160.31.1.el7	0:3.10.0-1160.31.1.el7
Red Hat:enterprise_linux:7::client	kernel-debug-devel	before 0:3.10.0-1160.31.1.el7	0:3.10.0-1160.31.1.el7
Red Hat:enterprise_linux:7::client	kernel-debuginfo	before 0:3.10.0-1160.31.1.el7	0:3.10.0-1160.31.1.el7

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
90Now
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 KEV
89Now
CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2021-3178Jan 19, 2021 · fs/nfsd/nfs3xdr.c in the Linux kernel through 5.10.8, when there is an NFS export of a subdirectory of a filesystem, allows remote attackers
27Monitor
← EarlierCVE-2020-35513Jan 26, 2021 · A flaw incorrect umask during file or directory modification in the Linux kernel NFS (network file system) functionality was found in the wa
19Monitor
Later →CVE-2021-3348Feb 1, 2021 · nbd_add_socket in drivers/block/nbd.c in the Linux kernel through 5.10.12 has an ndb_queue_rq use-after-free that could be triggered by loca
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
almalinux:kernel-abi-whitelists	4.18.0-240.22.1.el8_3 · AlmaLinux:8	Package registry (OSV)
almalinux:kernel-tools-libs-devel	4.18.0-240.22.1.el8_3 · AlmaLinux:8	Package registry (OSV)
debian:linux	5.10.12-1 · Debian:12	Package registry (OSV)
debian:linux-4.19	4.19.171-2~deb9u1 · Debian:9	Package registry (OSV)
opensuse:kernel-debug	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-default	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-default-base	5.3.18-lp152.63.1.lp152.8.21.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-docs	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-kvmsmall	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-obs-build	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-obs-qa	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-preempt	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-source	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:kernel-syms	5.3.18-lp152.63.1 · openSUSE:Leap 15.2	Package registry (OSV)
red hat:kernel-rt	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-core	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debug	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debug-core	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debug-debuginfo	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debug-devel	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debug-kvm	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debug-modules	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debug-modules-extra	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debuginfo	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-debuginfo-common-x86_64	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
red hat:kernel-rt-devel	0:4.18.0-240.22.1.rt7.77.el8_3 · Red Hat:enterprise_linux:8::nfv	Package registry (OSV)
suse:kernel-azure	5.3.18-18.35.2 · SUSE:Linux Enterprise Module for Public Cloud 15 SP2	Package registry (OSV)
suse:kernel-default	4.12.14-122.60.1 · SUSE:Linux Enterprise High Availability Extension 12 SP5	Package registry (OSV)
suse:kernel-default-base	5.3.18-24.49.2.9.21.2 · SUSE:Linux Enterprise Module for Basesystem 15 SP2	Package registry (OSV)
suse:kernel-docs	4.12.14-122.60.2 · SUSE:Linux Enterprise Software Development Kit 12 SP5	Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
Source	Kind	Date
Proof-of-concept repository on GitHub	stars:0	2022-04-26

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.

PublishedJan 29, 2021
First PoCApr 26, 2022+451 d
TodayOct 29, 2026+2099 d

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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 researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

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-21-0465 · Jun 10, 2021(RedHat Güvenlik Güncellemesi Yayınladı)
TR-21-0430 · May 31, 2021(RedHat Güvenlik Güncellemeleri Yayınladı)

All national notices →

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.
No special conditions are required; it is repeatable.

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: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:47 PM UTC

For records you follow, these changes also arrive as notifications. →

References

www.openwall.com/lists/oss-security/2021/01/29/4

Show all references (17 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records