CVE-2021-47099

Kernel crash via cloned buffers entering GRO

Published Mar 4, 2024 · Updated Aug 5, 2026

Denial of service in the Linux kernel veth driver 5.13 through 5.15.11 allows local users to trigger a kernel crash via TCP traffic. The veth NAPI path passes shared or cloned socket buffers into GRO without a share check when no XDP program is attached. Reachability requires GRO on a veth device, disabled TSO on its peer, and no attached XDP program; the resulting skb_shift BUG interrupts the host.

CVSS severity7.8
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux kernel veth driver 5.13 through 5.15.11 allows local users to trigger a kernel crash via TCP traffic. The veth NAPI path passes shared or cloned socket buffers into GRO without a share check when no XDP program is attached. Reachability requires GRO on a veth device, disabled TSO on its peer, and no attached XDP program; the resulting skb_shift BUG interrupts the host.

The record

CVE
CVE-2021-47099
Published
Mar 4, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 4, 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=5.13
  2. Affected versionversion=d3256efd8e8b234a6251e4d4580bd2c3c31fdc4c <9695b7de5b4760ed22132aca919570c0190cb0ce
  3. Affected versionversion=d3256efd8e8b234a6251e4d4580bd2c3c31fdc4c <d2269ae48598e05b59ec9ea9e6e44fd33941130d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.13; version=d3256efd8e8b234a6251e4d4580bd2c3c31fdc4c <9695b7de5b4760ed22132aca919570c0190cb0ce; version=d3256efd8e8b234a6251e4d4580bd2c3c31fdc4c <d2269ae48598e05b59ec9ea9e6e44fd33941130d

Published CVSS scores

7.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.0CISA-ADPCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

T1499Endpoint Denial of Service

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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