CVE-2025-68736 (GCVE-0-2025-68736)

Vulnerability from cvelistv5 – Published: 2025-12-24 12:09 – Updated: 2026-10-16 15:09
VLAI
Title
landlock: Fix handling of disconnected directories
Summary
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.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 15:04 UTC
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: cb2c7d1a1776057c9a1f48ed1250d85e94d4850d , < 4f5cdc82a6c7e22cfd9a92d203cec13a52a3f363 (git)
Affected: cb2c7d1a1776057c9a1f48ed1250d85e94d4850d , < fbf718d5afe21057694a0c0223a18b0c7a5960b6 (git)
Affected: cb2c7d1a1776057c9a1f48ed1250d85e94d4850d , < 426d5b681b2f3339ff04da39b81d71176dc8c87c (git)
Affected: cb2c7d1a1776057c9a1f48ed1250d85e94d4850d , < cadb28f8b3fd6908e3051e86158c65c3a8e1c907 (git)
Affected: cb2c7d1a1776057c9a1f48ed1250d85e94d4850d , < 49c9e09d961025b22e61ef9ad56aa1c21b6ce2f1 (git)
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Linux Linux Affected: 5.13
Unaffected: 0 , < 5.13 (semver)
Unaffected: 6.1.189 , ≤ 6.1.* (semver)
Unaffected: 6.6.143 , ≤ 6.6.* (semver)
Unaffected: 6.12.80 , ≤ 6.12.* (semver)
Unaffected: 6.18.2 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlandlock: Fix handling of disconnected directories\n\nDisconnected files or directories can appear when they are visible and\nopened from a bind mount, but have been renamed or moved from the source\nof the bind mount in a way that makes them inaccessible from the mount\npoint (i.e. out of scope).\n\nPreviously, access rights tied to files or directories opened through a\ndisconnected directory were collected by walking the related hierarchy\ndown to the root of the filesystem, without taking into account the\nmount point because it couldn\u0027t be found. This could lead to\ninconsistent access results, potential access right widening, and\nhard-to-debug renames, especially since such paths cannot be printed.\n\nFor a sandboxed task to create a disconnected directory, it needs to\nhave write access (i.e. FS_MAKE_REG, FS_REMOVE_FILE, and FS_REFER) to\nthe underlying source of the bind mount, and read access to the related\nmount point.   Because a sandboxed task cannot acquire more access\nrights than those defined by its Landlock domain, this could lead to\ninconsistent access rights due to missing permissions that should be\ninherited from the mount point hierarchy, while inheriting permissions\nfrom the filesystem hierarchy hidden by this mount point instead.\n\nLandlock now handles files and directories opened from disconnected\ndirectories by taking into account the filesystem hierarchy when the\nmount point is not found in the hierarchy walk, and also always taking\ninto account the mount point from which these disconnected directories\nwere opened.  This ensures that a rename is not allowed if it would\nwiden access rights [1].\n\nThe rationale is that, even if disconnected hierarchies might not be\nvisible or accessible to a sandboxed task, relying on the collected\naccess rights from them improves the guarantee that access rights will\nnot be widened during a rename because of the access right comparison\nbetween the source and the destination (see LANDLOCK_ACCESS_FS_REFER).\nIt may look like this would grant more access on disconnected files and\ndirectories, but the security policies are always enforced for all the\nevaluated hierarchies.  This new behavior should be less surprising to\nusers and safer from an access control perspective.\n\nRemove a wrong WARN_ON_ONCE() canary in collect_domain_accesses() and\nfix the related comment.\n\nBecause opened files have their access rights stored in the related file\nsecurity properties, there is no impact for disconnected or unlinked\nfiles."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nlandlock: Correcci\u00f3n del manejo de directorios desconectados\n\nArchivos o directorios desconectados pueden aparecer cuando son visibles y se abren desde un montaje de enlace, pero han sido renombrados o movidos desde el origen del montaje de enlace de una manera que los hace inaccesibles desde el punto de montaje (es decir, fuera de alcance).\n\nAnteriormente, los derechos de acceso vinculados a archivos o directorios abiertos a trav\u00e9s de un directorio desconectado se recopilaban recorriendo la jerarqu\u00eda relacionada hasta la ra\u00edz del sistema de archivos, sin tener en cuenta el punto de montaje porque no se pod\u00eda encontrar. Esto podr\u00eda llevar a resultados de acceso inconsistentes, una posible ampliaci\u00f3n de los derechos de acceso y renombramientos dif\u00edciles de depurar, especialmente porque tales rutas no pueden imprimirse.\n\nPara que una tarea en sandbox cree un directorio desconectado, necesita tener acceso de escritura (es decir, FS_MAKE_REG, FS_REMOVE_FILE y FS_REFER) al origen subyacente del montaje de enlace, y acceso de lectura al punto de montaje relacionado. Debido a que una tarea en sandbox no puede adquirir m\u00e1s derechos de acceso que los definidos por su dominio Landlock, esto podr\u00eda llevar a derechos de acceso inconsistentes debido a permisos faltantes que deber\u00edan heredarse de la jerarqu\u00eda del punto de montaje, mientras que, en su lugar, hereda permisos de la jerarqu\u00eda del sistema de archivos oculta por este punto de montaje.\n\nLandlock ahora maneja archivos y directorios abiertos desde directorios desconectados teniendo en cuenta la jerarqu\u00eda del sistema de archivos cuando el punto de montaje no se encuentra en el recorrido de la jerarqu\u00eda, y tambi\u00e9n siempre teniendo en cuenta el punto de montaje desde el cual se abrieron estos directorios desconectados. Esto asegura que no se permite un renombramiento si ampliara los derechos de acceso [1].\n\nLa raz\u00f3n es que, incluso si las jerarqu\u00edas desconectadas podr\u00edan no ser visibles o accesibles para una tarea en sandbox, confiar en los derechos de acceso recopilados de ellas mejora la garant\u00eda de que los derechos de acceso no se ampliar\u00e1n durante un renombramiento debido a la comparaci\u00f3n de derechos de acceso entre el origen y el destino (ver LANDLOCK_ACCESS_FS_REFER). Podr\u00eda parecer que esto otorgar\u00eda m\u00e1s acceso a archivos y directorios desconectados, pero las pol\u00edticas de seguridad siempre se aplican para todas las jerarqu\u00edas evaluadas. Este nuevo comportamiento deber\u00eda ser menos sorprendente para los usuarios y m\u00e1s seguro desde una perspectiva de control de acceso.\n\nEliminar un canary WARN_ON_ONCE() incorrecto en collect_domain_accesses() y corregir el comentario relacionado.\n\nDebido a que los archivos abiertos tienen sus derechos de acceso almacenados en las propiedades de seguridad de archivo relacionadas, no hay impacto para archivos desconectados o desvinculados."
          }
        ],
        "id": "CVE-2025-68736",
        "lastModified": "2026-10-16T15:16:52.470",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
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              "exploitabilityScore": 2.0,
              "impactScore": 6.0,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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              "ssvcData": {
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                "options": [
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                  {
                    "technicalImpact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T15:04:56.596972Z",
                "version": "2.0.3"
              }
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        "published": "2025-12-24T13:16:28.550",
        "references": [
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Deferred"
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    "redhat_vex": {
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      "current_release_date": "2026-07-30T08:33:50+00:00",
      "cve": "CVE-2025-68736",
      "id": "CVE-2025-68736",
      "initial_release_date": "2025-12-24T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: landlock: Fix handling of disconnected directories",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-68736.json",
      "version": "3"
    },
    "vulnrichment": {
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                      },
                      {
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                      }
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                    "timestamp": "2026-10-16T15:04:56.596972Z",
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              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
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              "product": "Linux",
              "programFiles": [
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              "vendor": "Linux",
              "versions": [
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                },
                {
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                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
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                  "version": "6.1.189",
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                  "version": "6.6.143",
                  "versionType": "semver"
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                  "version": "6.12.80",
                  "versionType": "semver"
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                  "version": "6.18.2",
                  "versionType": "semver"
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                  "status": "unaffected",
                  "version": "6.19",
                  "versionType": "original_commit_for_fix"
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              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlandlock: Fix handling of disconnected directories\n\nDisconnected files or directories can appear when they are visible and\nopened from a bind mount, but have been renamed or moved from the source\nof the bind mount in a way that makes them inaccessible from the mount\npoint (i.e. out of scope).\n\nPreviously, access rights tied to files or directories opened through a\ndisconnected directory were collected by walking the related hierarchy\ndown to the root of the filesystem, without taking into account the\nmount point because it couldn\u0027t be found. This could lead to\ninconsistent access results, potential access right widening, and\nhard-to-debug renames, especially since such paths cannot be printed.\n\nFor a sandboxed task to create a disconnected directory, it needs to\nhave write access (i.e. FS_MAKE_REG, FS_REMOVE_FILE, and FS_REFER) to\nthe underlying source of the bind mount, and read access to the related\nmount point.   Because a sandboxed task cannot acquire more access\nrights than those defined by its Landlock domain, this could lead to\ninconsistent access rights due to missing permissions that should be\ninherited from the mount point hierarchy, while inheriting permissions\nfrom the filesystem hierarchy hidden by this mount point instead.\n\nLandlock now handles files and directories opened from disconnected\ndirectories by taking into account the filesystem hierarchy when the\nmount point is not found in the hierarchy walk, and also always taking\ninto account the mount point from which these disconnected directories\nwere opened.  This ensures that a rename is not allowed if it would\nwiden access rights [1].\n\nThe rationale is that, even if disconnected hierarchies might not be\nvisible or accessible to a sandboxed task, relying on the collected\naccess rights from them improves the guarantee that access rights will\nnot be widened during a rename because of the access right comparison\nbetween the source and the destination (see LANDLOCK_ACCESS_FS_REFER).\nIt may look like this would grant more access on disconnected files and\ndirectories, but the security policies are always enforced for all the\nevaluated hierarchies.  This new behavior should be less surprising to\nusers and safer from an access control perspective.\n\nRemove a wrong WARN_ON_ONCE() canary in collect_domain_accesses() and\nfix the related comment.\n\nBecause opened files have their access rights stored in the related file\nsecurity properties, there is no impact for disconnected or unlinked\nfiles."
            }
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                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
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                  "value": "AV:L - The vulnerable Landlock checks are reached through local renameat(2), renameat2(2), or linkat(2) operations using a descriptor into a bind-mounted directory; no network path exists.\nAC:L - Given the required bind-mount layout, the attacker can deterministically open the directory, rename the source subtree to disconnect it, and perform the refer operation without a race or uncontrolled condition.\nPR:L - Ordinary DAC write/search permissions and granted Landlock REFER, MAKE, and REMOVE rights suffice; no capability in the initial user namespace is required, and the mount can be prepared before confinement or through user and mount namespaces.\nUI:N - The confined attacker performs the complete descriptor, rename, and link sequence without another user\u0027s participation.\nS:C - The flaw bypasses the Landlock sandbox boundary and affects host filesystem resources that the sandbox policy was intended to place under a separate security authority.\nC:H - Incorrect hierarchy comparison can let the attacker relocate otherwise denied files into a hierarchy granting read access, potentially exposing sensitive files throughout an affected bind-mounted tree.\nI:H - The widened rights can include WRITE_FILE, TRUNCATE, REMOVE, MAKE, and REFER, permitting unauthorized modification, replacement, or deletion of protected files allowed by the underlying DAC policy.\nA:H - The attacker-controlled path triggers WARN_ON_ONCE(), which causes a kernel panic when panic_on_warn or an applicable warning limit is enabled; widened write and removal rights can also destroy availability-critical files."
                }
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            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2025-68736",
        "datePublished": "2025-12-24T12:09:35.081Z",
        "dateReserved": "2025-12-24T10:30:51.029Z",
        "dateUpdated": "2026-10-16T15:09:43.754Z",
        "state": "PUBLISHED"
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}



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