CVE-2026-34078: flatpak UNIX Symbolic Link (Symlink) Following
Vulnerability summary
CVE-2026-34078 is a critical (CVSS 10.0) UNIX Symbolic Link (Symlink) Following vulnerability in flatpak. EPSS estimates a 0.90% chance of exploitation in the next 30 days, higher than 59.1% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 17 · Related 5Timeline
- 07-04-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
7 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated9.3CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- NVDNIST9.3CriticalCVSS: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:X
- CVE.orgCNA9.0CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:HDiffers
- OSV · UbuntuEcosystem advisory · calculated10.0CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated10.0CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS trend
Probability
0.90%
Chance of exploitation in the next 30 days
Percentile
59%
Versus all other CVEs
30-day change
-0.78 pp
From 1.68% on 21-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-61UNIX Symbolic Link (Symlink) FollowingThe product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.
- CWE-59Improper Link Resolution Before File Access ('Link Following')The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
Affected systems
Debian1 product
- flatpak< 1.14.10-1~deb12u2 | < 1.16.6-1~deb13u1 | < 1.16.4-1
Flatpak1 product
- flatpak< 1.16.4 | ≤ 1.16.3
Ubuntu1 product
- flatpakAll versions (No fix recorded) | < 1.6.5-0ubuntu0.5+esm1 | < 1.12.7-1ubuntu0.1+esm1 | < 1.14.6-1ubuntu0.1+esm1
3 vendors · 3 products
References
21 links- github.com/flatpak/flatpak/security/advisories/GHSA-cc2q-qc34-jprgX Refsource CONFIRMREPORTVendor Advisory
