CVE-2021-3592

Host-memory disclosure via undersized BOOTP packet

Published Jun 15, 2021 · Updated Aug 3, 2024

Host-memory disclosure in libslirp before 4.6.0 allows guest OS users to read 10 bytes of host heap data through a crafted BOOTP packet. bootp_input casts an undersized UDP mbuf to bootp_t without checking that the complete structure is present, then copies out-of-buffer fields into its reply. Control of a guest using SLiRP user-mode networking is required, and the demonstrated consequence is limited to disclosure of 10 host heap bytes per response.

CVSS severity3.8
Low
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Host-memory disclosure in libslirp before 4.6.0 allows guest OS users to read 10 bytes of host heap data through a crafted BOOTP packet. bootp_input casts an undersized UDP mbuf to bootp_t without checking that the complete structure is present, then copies out-of-buffer fields into its reply. Control of a guest using SLiRP user-mode networking is required, and the demonstrated consequence is limited to disclosure of 10 host heap bytes per response.

The record

CVE
CVE-2021-3592
Published
Jun 15, 2021
Updated
Aug 3, 2024
Vendor
Libslirp Project
Product
libslirp
Classifications
CWE-908
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=libslirp 4.6.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Libslirp Project · libslirpversion=libslirp 4.6.0

Published CVSS scores

3.8UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
3.8Oracle LinuxCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
3.8Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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