CVE-2021-42762

Sandbox bypass via deletable confinement marker

Published Oct 20, 2021 · Updated Aug 4, 2024

Sandbox bypass in WebKitGTK and WPE WebKit before 2.34.1 allows local users to mislead host services via a sandboxed process. BubblewrapLauncher.cpp leaves clone3 and newer mount-manipulation syscalls usable, allowing the web process to alter its VFS namespace and delete the .flatpak-info confinement marker. Exploitation requires code execution inside the Linux web-process sandbox; only host services exposed through mounted UNIX sockets can be misled, and the process otherwise remains confined.

CVSS severity5.3
Medium
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sandbox bypass in WebKitGTK and WPE WebKit before 2.34.1 allows local users to mislead host services via a sandboxed process. BubblewrapLauncher.cpp leaves clone3 and newer mount-manipulation syscalls usable, allowing the web process to alter its VFS namespace and delete the .flatpak-info confinement marker. Exploitation requires code execution inside the Linux web-process sandbox; only host services exposed through mounted UNIX sockets can be misled, and the process otherwise remains confined.

The record

CVE
CVE-2021-42762
Published
Oct 20, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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