# CVE-2025-68736: landlock: Fix handling of disconnected directories > A flaw in Linux kernel Landlock allows sandboxed tasks to widen access rights via disconnected directories, potentially bypassing security restrictions. - **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 24 Dec 2025 - **Updated:** 16 Oct 2026 - **Also known as:** AZL-73084, BELL-CVE-2025-68736, DEBIAN-CVE-2025-68736, GHSA-pxr4-9wxh-g3jr, ROOT-OS-DEBIAN-12-CVE-2025-68736, ROOT-OS-DEBIAN-13-CVE-2025-68736, ROOT-OS-UBUNTU-2204-CVE-2025-68736, ROOT-OS-UBUNTU-2404-CVE-2025-68736, UBUNTU-CVE-2025-68736 ## What is CVE-2025-68736? CVE-2025-68736 is a high-severity vulnerability in Linux, published on 24 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: landlock: Fix handling of disconnected directories Disconnected files or directories can appear when they are visible and opened from a bind mount, but have been renamed or moved from the source of the bind mount in a way that makes them inaccessible from the mount point (i.e. out of scope). Previously, access rights tied to files or directories opened through a disconnected directory were collected by walking the related hierarchy down to the root of the filesystem, without taking into account the mount point because it couldn't be found. This could lead to inconsistent access results, potential access right widening, and hard-to-debug renames, especially since such paths cannot be printed. For a sandboxed task to create a disconnected directory, it needs to have write access (i.e. FS_MAKE_REG, FS_REMOVE_FILE, and FS_REFER) to the underlying source of the bind mount, and read access to the related mount point. Because a sandboxed task cannot acquire more access rights than those defined by its Landlock domain, this could lead to inconsistent access rights due to missing permissions that should be inherited from the mount point hierarchy, while inheriting permissions from the filesystem hierarchy hidden by this mount point instead. Landlock now handles files and directories opened from disconnected directories by taking into account the filesystem hierarchy when the mount point is not found in the hierarchy walk, and also always taking into account the mount point from which these disconnected directories were opened. This ensures that a rename is not allowed if it would widen access rights [1]. The rationale is that, even if disconnected hierarchies might not be visible or accessible to a sandboxed task, relying on the collected access rights from them improves the guarantee that access rights will not be widened during a rename because of the access right comparison between the source and the destination (see LANDLOCK_ACCESS_FS_REFER). It may look like this would grant more access on disconnected files and directories, but the security policies are always enforced for all the evaluated hierarchies. This new behavior should be less surprising to users and safer from an access control perspective. Remove a wrong WARN_ON_ONCE() canary in collect_domain_accesses() and fix the related comment. Because opened files have their access rights stored in the related file security properties, there is no impact for disconnected or unlinked files. ## Which versions are affected by CVE-2025-68736? ## How do I fix CVE-2025-68736? Apply the vendor's patch. ## Is CVE-2025-68736 being exploited? There is no known exploitation of CVE-2025-68736 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2025-68736 and fix it if it is affected. What it is: CVE-2025-68736 is a high-severity vulnerability in Linux, published on 24 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2025-68736 in the wild and no public exploit code. Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2025-68736/ (Markdown: https://insights.sbomify.com/CVE-2025-68736/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68736 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68736 - OSV: https://osv.dev/vulnerability/CVE-2025-68736 --- From sbomify Insights: https://insights.sbomify.com/CVE-2025-68736/ Summaries are generated and may contain mistakes; the official description above is the record.