CVE-2026-34078

Host code execution via symlinked sandbox-expose paths

Published Apr 7, 2026 · Updated Apr 7, 2026

Sandbox escape in Flatpak before 1.16.4 allows attackers to read and write host files and execute code through a sandboxed app. The Flatpak portal accepts app-controlled symlinks in sandbox-expose paths, and flatpak run bind-mounts each resolved host target into the sandbox. A malicious Flatpak app requires the Flatpak portal to be enabled; the resulting host-file access supplies a primitive for execution in the host context.

CVSS severity9.3
Critical
EPSS probability1.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sandbox escape in Flatpak before 1.16.4 allows attackers to read and write host files and execute code through a sandboxed app. The Flatpak portal accepts app-controlled symlinks in sandbox-expose paths, and flatpak run bind-mounts each resolved host target into the sandbox. A malicious Flatpak app requires the Flatpak portal to be enabled; the resulting host-file access supplies a primitive for execution in the host context.

The record

CVE
CVE-2026-34078
Published
Apr 7, 2026
Updated
Apr 7, 2026
Vendor
Libslirp Project
Product
Flatpak
Classifications
CWE-61, CWE-59, T1611
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 2026Record 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=< 1.16.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Libslirp Project · Flatpakversion=< 1.16.4

Published CVSS scores

9.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
10.0NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
9.0Red HatCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/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.

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

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-61UNIX Symbolic Link (Symlink) Following
CWE-59Improper Link Resolution Before File Access ('Link Following')
T1611Escape to Host

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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