CVE-2021-46998

Local privilege escalation via enic transmit use-after-free

Published Feb 28, 2024 · Updated Aug 5, 2026

Use-after-free in the Cisco enic Ethernet driver in Linux allows local users to escalate privileges through packet transmission. When enic_queue_wq_skb encounters an error, it frees the socket buffer, but enic_hard_start_xmit then passes that freed buffer to skb_tx_timestamp. An unprivileged local user must transmit through an active enic interface and induce a DMA-mapping failure; exploitation can disclose or corrupt kernel memory, escalate privileges, or panic the host.

CVSS severity7.8
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Cisco enic Ethernet driver in Linux allows local users to escalate privileges through packet transmission. When enic_queue_wq_skb encounters an error, it frees the socket buffer, but enic_hard_start_xmit then passes that freed buffer to skb_tx_timestamp. An unprivileged local user must transmit through an active enic interface and induce a DMA-mapping failure; exploitation can disclose or corrupt kernel memory, escalate privileges, or panic the host.

The record

CVE
CVE-2021-46998
Published
Feb 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.16
  2. Affected versionversion=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <25a87b1f566b5eb2af2857a928f0e2310d900976
  3. Affected versionversion=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <643001b47adc844ae33510c4bb93c236667008a3
  4. Affected versionversion=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <6892396ebf04ea2c021d80e10f4075e014cd7cc3
  5. Affected versionversion=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <7afdd6aba95c8a526038e7abe283eeac3e4320f1
  6. Affected versionversion=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <d90529392aaf498dafa95d212295d64b2cea4e24
  7. Affected versionversion=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <f7f6f07774091a6ddd98500b85386c3c6afb30d3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.16; version=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <25a87b1f566b5eb2af2857a928f0e2310d900976; version=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <643001b47adc844ae33510c4bb93c236667008a3; version=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <6892396ebf04ea2c021d80e10f4075e014cd7cc3; version=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <7afdd6aba95c8a526038e7abe283eeac3e4320f1; version=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <d90529392aaf498dafa95d212295d64b2cea4e24; version=fb7516d42478ebc8e2f00efb76ef96f7b68fd8d3 <f7f6f07774091a6ddd98500b85386c3c6afb30d3

Published CVSS scores

7.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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