NVD / CVE Program· CNA Linux

CVE-2021-46998: ethernet:enic: Fix a use after free bug in enic_hard_start_xmit

HighCVSS 7.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

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: 0.24% (FIRST EPSS).
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: Linux Linux 25a87b1f566b5eb2af2857a928f0e2310d900976, 643001b47adc844ae33510c4bb93c236667008a3, 6892396ebf04ea2c021d80e10f4075e014cd7cc3.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 25a87b1f566b5eb2af2857a928f0e2310d900976, 643001b47adc844ae33510c4bb93c236667008a3, 6892396ebf04ea2c021d80e10f4075e014cd7cc3 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

In the Linux kernel, the following vulnerability has been resolved: ethernet:enic: Fix a use after free bug in enic_hard_start_xmit In enic_hard_start_xmit, it calls enic_queue_wq_skb(). Inside enic_queue_wq_skb, if some error happens, the skb will be freed by dev_kfree_skb(skb). But the freed skb is still used in skb_tx_timestamp(skb). My patch makes enic_queue_wq_skb() return error and goto spin_unlock() incase of error. The solution is provided by Govind. See https://lkml.org/lkml/2021/4/30/961.

Memory safety

Published: Feb 28, 2024
Updated: Aug 5, 2026
EPSS: 0.2% · 15th 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 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 7.8
CNA · Linux: 7.8; agree

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.

Is your version affected? Check it

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 help

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

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

Linux Linux
- 4.16affected
- fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 and later · before 25a87b1f566b5eb2af2857a928f0e2310d900976affected · git
- fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 and later · before f7f6f07774091a6ddd98500b85386c3c6afb30d3affected · git
- fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 and later · before 7afdd6aba95c8a526038e7abe283eeac3e4320f1affected · git
- fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 and later · before 6892396ebf04ea2c021d80e10f4075e014cd7cc3affected · git
- fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 and later · before d90529392aaf498dafa95d212295d64b2cea4e24affected · git
- fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 and later · before 643001b47adc844ae33510c4bb93c236667008a3affected · git
- before 4.16not affected · semver
- 4.19.191 and later · up to and including 4.19.*not affected · semver
- 5.4.120 and later · up to and including 5.4.*not affected · semver

Affected versions · NVD (5)

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

linux linux kernel4.16 and later · before 4.19.191
linux linux kernel4.20 and later · before 5.4.120
linux linux kernel5.5 and later · before 5.10.38
linux linux kernel5.11 and later · before 5.11.22
linux linux kernel5.12 and later · before 5.12.5

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
SUSE:Linux Enterprise Real Time 12 SP5	kernel-rt	before 4.12.14-10.182.1	4.12.14-10.182.1
SUSE:Linux Enterprise Real Time 12 SP5	kernel-rt_debug	before 4.12.14-10.182.1	4.12.14-10.182.1
SUSE:Linux Enterprise Real Time 12 SP5	kernel-source-rt	before 4.12.14-10.182.1	4.12.14-10.182.1
SUSE:Linux Enterprise Real Time 12 SP5	kernel-syms-rt	before 4.12.14-10.182.1	4.12.14-10.182.1
SUSE:Linux Enterprise Server 12 SP5	kernel-azure	before 4.12.14-16.182.1	4.12.14-16.182.1
SUSE:Linux Enterprise Server 12 SP5	kernel-source-azure	before 4.12.14-16.182.1	4.12.14-16.182.1
SUSE:Linux Enterprise Server 12 SP5	kernel-syms-azure	before 4.12.14-16.182.1	4.12.14-16.182.1

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-2021-46996Feb 28, 2024 · netfilter: nftables: Fix a memleak from userdata error path in new objects
22Monitor
← EarlierCVE-2021-46997Feb 28, 2024 · arm64: entry: always set GIC_PRIO_PSR_I_SET during entry
22Monitor
Later →CVE-2021-46999Feb 28, 2024 · sctp: do asoc update earlier in sctp_sf_do_dupcook_a
31Monitor

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
Linux Linux	25a87b1f566b5eb2af2857a928f0e2310d900976	Vendor (CNA)
Linux Linux	643001b47adc844ae33510c4bb93c236667008a3	Vendor (CNA)
Linux Linux	6892396ebf04ea2c021d80e10f4075e014cd7cc3	Vendor (CNA)
Linux Linux	7afdd6aba95c8a526038e7abe283eeac3e4320f1	Vendor (CNA)
Linux Linux	d90529392aaf498dafa95d212295d64b2cea4e24	Vendor (CNA)
Linux Linux	f7f6f07774091a6ddd98500b85386c3c6afb30d3	Vendor (CNA)
debian:linux	5.10.38-1 · Debian:12	Package registry (OSV)
suse:kernel-azure	4.12.14-16.182.1 · SUSE:Linux Enterprise Server 12 SP5	Package registry (OSV)
suse:kernel-rt	4.12.14-10.182.1 · SUSE:Linux Enterprise Real Time 12 SP5	Package registry (OSV)
suse:kernel-rt_debug	4.12.14-10.182.1 · SUSE:Linux Enterprise Real Time 12 SP5	Package registry (OSV)
suse:kernel-source-azure	4.12.14-16.182.1 · SUSE:Linux Enterprise Server 12 SP5	Package registry (OSV)
suse:kernel-source-rt	4.12.14-10.182.1 · SUSE:Linux Enterprise Real Time 12 SP5	Package registry (OSV)
suse:kernel-syms-azure	4.12.14-16.182.1 · SUSE:Linux Enterprise Server 12 SP5	Package registry (OSV)
suse:kernel-syms-rt	4.12.14-10.182.1 · SUSE:Linux Enterprise Real Time 12 SP5	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.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-24-0145 · Feb 29, 2024(Linux Kernel Güncellemesi)

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

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 (1)

Fix✗ → ✓Sep 28, 2026, 10:09 PM UTC

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

References

git.kernel.org/stable/c/25a87b1f566b5eb2af2857a928f0e2310d900976

Show all references (5 more)

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

All records