CVE-2026-34078
Flatpak ≤ 1.16.3
Raw vector
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2026-34078 is a critical-severity UNIX Symbolic Link (Symlink) Following (CWE-61) vulnerability in Flatpak Flatpak. Its CVSS base score is 9.3 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked in the top 25% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-34078 is a critical vulnerability in Flatpak, a Linux application sandboxing and distribution framework, affecting versions prior to 1.16.4. The issue stems from the Flatpak portal accepting paths in the sandbox-expose options that can be controlled by applications as symbolic links pointing to arbitrary host paths. When Flatpak run processes these, it mounts the resolved host path inside the sandbox, bypassing intended isolation and exposing host files to the sandboxed application. This flaw, associated with CWE-61 (Symbolic Link Race Condition), carries a CVSS v3.1 base score of 10.0 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H).
The vulnerability can be exploited by remote attackers with no privileges or user interaction required, typically through a malicious Flatpak application distributed via untrusted sources. An attacker crafts an app-controlled symlink in the sandbox-expose options to target sensitive host paths, granting the sandboxed app read/write access to arbitrary host files upon execution via Flatpak run. This access serves as a primitive for achieving code execution in the host context, potentially leading to full system compromise on affected Linux systems using vulnerable Flatpak installations.
Advisories, including the Flatpak GitHub security advisory (GHSA-cc2q-qc34-jprg) and discussions on oss-security mailing lists, confirm the vulnerability is fixed in Flatpak 1.16.4. Security practitioners should prioritize upgrading to version 1.16.4 or later and review Flatpak configurations for exposed paths, particularly in environments distributing third-party Flatpak apps.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-19970
Vulnerability Data
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.…
more
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 2 hardening rules · 2 OS baselines
V15.4.2V5.2.5
Mitigating Controls (NIST 800-53 r5) AI
Access enforcement must resolve the actual target of any file reference and apply authorizations to it, directly stopping symlink traversal to unauthorized objects.
Information-flow enforcement on file operations must follow the resolved target rather than the link name, blocking unauthorized data movement via symlinks.
Least-privilege restrictions on the directories that may contain links or targets reduce the set of files an attacker can reach even if a symlink is followed.
Validating file-name inputs can reject or canonicalize names that resolve to links before access occurs.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly prevent introduction of symlink-following flaws in file-handling code.
Vulnerability identification can discover existing symlink issues but does not prevent or remediate them in code.
Least-privilege access policies can limit damage from symlink attacks but do not address the coding flaw itself.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect symlink-following vulnerabilities before deployment, covering most of the weakness.
Secure SDLC practices can mandate link-resolution checks and canonicalization before file access.
Application security requirements can explicitly require safe handling of symbolic links and path traversal.
Secure-architecture principles require safe file-handling and canonicalization, directly addressing symlink attacks.
Secure-coding standards mandate explicit symlink checks and safe open patterns, fully mitigating CWE-61.
Access-control rules can restrict which files a process may open, reducing symlink-following risk but not eliminating the underlying path-resolution flaw.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (1 rule)
- V-248577 OL 8 must enable kernel parameters to enforce Discretionary Access Control (DAC) on symlinks. prevents CWE-61