CVE-2026-34078 — Flatpak has a complete sandbox escape leading to host file access and code execution in the host context

Flatpak is a Linux application sandboxing and distribution framework. Prior to 1.16.4, the Flatpak portal accepts paths in the sandbox-expose options which can be app-controlled symlinks pointing at arbitrary paths. Flatpak run mounts the resolved host path in the sandbox. This gives apps access to all host files and can be used as a primitive to gain code execution in the host context. This vulnerability is fixed in 1.16.4.

Published Apr 7, 2026Updated Jul 15, 2026Sources: cvelistV5, GitHub_M

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

chance of exploitation in 30 days

Affects

flatpak

15 products listed

CVSS base

CRITICAL

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (2)

flatpak redhat

Products (15)

flatpakred hat enterprise linux 10red hat enterprise linux 10 0 extended update supportred hat enterprise linux 7 extended lifecycle supportred hat enterprise linux 8red hat enterprise linux 8 4 advanced mission critical update supportred hat enterprise linux 8 4 extended update support long life add onred hat enterprise linux 8 6 advanced mission critical update supportred hat enterprise linux 8 6 extended update support long life add onred hat enterprise linux 8 8 telecommunications update servicered hat enterprise linux 8 8 update services for sap solutionsred hat enterprise linux 9red hat enterprise linux 9 2 update services for sap solutionsred hat enterprise linux 9 4 update services for sap solutionsred hat enterprise linux 9 6 extended update support

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
9	CVSS 3.1	CRITICAL	—	—	cvelistV5

Weakness & attack patterns

CWE-61
CWE-59

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

T1547.009Boot or Logon Autostart Execution: Shortcut Modification
T1574.005Hijack Execution Flow: Executable Installer File Permissions Weakness
T1574.010Hijack Execution Flow: Services File Permissions Weakness

References

17 on the record

github.com/flatpak/flatpak/security/advisories/GHSA-cc2q-qc34-jprg
x_refsource_CONFIRM
www.openwall.com/lists/oss-security/2026/04/09/8
reference
www.openwall.com/lists/oss-security/2026/04/10/14
reference
access.redhat.com/security/cve/CVE-2026-34078
vdb-entry, x_refsource_REDHAT
bugzilla.redhat.com/show_bug.cgi?id=2456276
issue-tracking, x_refsource_REDHAT
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34078.json
x_sadp-csaf-vex
access.redhat.com/errata/RHSA-2026:35843
vendor-advisory, x_refsource_REDHAT
access.redhat.com/errata/RHSA-2026:23420
vendor-advisory, x_refsource_REDHAT

Elsewhere on this site

flatpakevery CVE for this vendor
redhatevery CVE for this vendor
CWE-61other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.