CVE-2021-2321Public exploit

Host-memory disclosure via E1000 descriptor underflow

Published Apr 28, 2021 · Updated Sep 26, 2024

Out-of-bounds read in Oracle VM VirtualBox Core before 6.1.20 allows guest OS users to disclose host memory through crafted E1000 frames. The e1kXmitDesc path returns early for an EOP descriptor marked done, leaving u16TxPktLen stale; a later length underflow lets e1kInsertChecksum read beyond aTxPacketFallback. Exploitation requires high-privileged code in a guest configured with the E1000 adapter, and the demonstrated consequence is disclosure of memory adjacent to the transmit buffer.

CVSS severity6.0
Medium
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Out-of-bounds read in Oracle VM VirtualBox Core before 6.1.20 allows guest OS users to disclose host memory through crafted E1000 frames. The e1kXmitDesc path returns early for an EOP descriptor marked done, leaving u16TxPktLen stale; a later length underflow lets e1kInsertChecksum read beyond aTxPacketFallback. Exploitation requires high-privileged code in a guest configured with the E1000 adapter, and the demonstrated consequence is disclosure of memory adjacent to the transmit buffer.

The record

CVE
CVE-2021-2321
Published
Apr 28, 2021
Updated
Sep 26, 2024
Vendor
Oracle Corporation
Product
Oracle VM VirtualBox
Classifications
CWE-125
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Apr 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 26, 2024Record 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=unspecified <6.1.20

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Oracle Corporation · Oracle VM VirtualBoxversion=unspecified <6.1.20

Published CVSS scores

2.1NIST NVDAV:L/AC:L/Au:N/C:P/I:N/A:N
6.0OracleCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo