Vulnerability-Lookup

UBUNTU-CVE-2026-96808 (CVE-2026-96808)

Vulnerability from osv_ubuntu – Published: 2026-09-23 17:17 – Updated: 2026-09-30 21:39 – Source website

Details

In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session's directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation.

Severity

7.4 (High)


                    
                      CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-96808	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-96808	REPORT
	https://github.com/flatpak/flatpak/security/advis…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "flatpak",
            "binary_version": "1.0.9-0ubuntu0.4+esm1"
          },
          {
            "binary_name": "flatpak-tests",
            "binary_version": "1.0.9-0ubuntu0.4+esm1"
          },
          {
            "binary_name": "gir1.2-flatpak-1.0",
            "binary_version": "1.0.9-0ubuntu0.4+esm1"
          },
          {
            "binary_name": "libflatpak0",
            "binary_version": "1.0.9-0ubuntu0.4+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "flatpak",
        "purl": "pkg:deb/ubuntu/flatpak@1.0.9-0ubuntu0.4+esm1?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.8.7-5",
        "0.10.0-1",
        "0.10.0-2",
        "0.10.1-1",
        "0.10.2-1",
        "0.10.2.1-1",
        "0.10.2.1-2",
        "0.10.3-1",
        "0.11.1-0ubuntu1",
        "0.11.3-2",
        "0.11.3-3",
        "0.11.7-0ubuntu0.1",
        "1.0.1-0ubuntu0.1",
        "1.0.6-0ubuntu0.1",
        "1.0.7-0ubuntu0.18.04.1",
        "1.0.8-0ubuntu0.18.04.1",
        "1.0.9-0ubuntu0.1",
        "1.0.9-0ubuntu0.2",
        "1.0.9-0ubuntu0.3",
        "1.0.9-0ubuntu0.4",
        "1.0.9-0ubuntu0.4+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "flatpak",
            "binary_version": "1.6.5-0ubuntu0.5+esm1"
          },
          {
            "binary_name": "flatpak-tests",
            "binary_version": "1.6.5-0ubuntu0.5+esm1"
          },
          {
            "binary_name": "gir1.2-flatpak-1.0",
            "binary_version": "1.6.5-0ubuntu0.5+esm1"
          },
          {
            "binary_name": "libflatpak0",
            "binary_version": "1.6.5-0ubuntu0.5+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "flatpak",
        "purl": "pkg:deb/ubuntu/flatpak@1.6.5-0ubuntu0.5+esm1?arch=source\u0026distro=esm-apps/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.4.3-1",
        "1.6.0-1",
        "1.6.1-1",
        "1.6.2-1",
        "1.6.3-1",
        "1.6.5-0ubuntu0.1",
        "1.6.5-0ubuntu0.2",
        "1.6.5-0ubuntu0.3",
        "1.6.5-0ubuntu0.4",
        "1.6.5-0ubuntu0.5",
        "1.6.5-0ubuntu0.5+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "flatpak",
            "binary_version": "1.12.7-1ubuntu0.1+esm1"
          },
          {
            "binary_name": "flatpak-tests",
            "binary_version": "1.12.7-1ubuntu0.1+esm1"
          },
          {
            "binary_name": "gir1.2-flatpak-1.0",
            "binary_version": "1.12.7-1ubuntu0.1+esm1"
          },
          {
            "binary_name": "libflatpak0",
            "binary_version": "1.12.7-1ubuntu0.1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "flatpak",
        "purl": "pkg:deb/ubuntu/flatpak@1.12.7-1ubuntu0.1+esm1?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.10.2-3",
        "1.12.2-1",
        "1.12.2-2",
        "1.12.3-1",
        "1.12.4-1",
        "1.12.5-1",
        "1.12.6-1",
        "1.12.7-1",
        "1.12.7-1ubuntu0.1",
        "1.12.7-1ubuntu0.1+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "flatpak",
            "binary_version": "1.14.6-1ubuntu0.1+esm1"
          },
          {
            "binary_name": "flatpak-tests",
            "binary_version": "1.14.6-1ubuntu0.1+esm1"
          },
          {
            "binary_name": "gir1.2-flatpak-1.0",
            "binary_version": "1.14.6-1ubuntu0.1+esm1"
          },
          {
            "binary_name": "libflatpak0",
            "binary_version": "1.14.6-1ubuntu0.1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "flatpak",
        "purl": "pkg:deb/ubuntu/flatpak@1.14.6-1ubuntu0.1+esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.14.4-2",
        "1.14.5-1",
        "1.14.5-1build1",
        "1.14.5-1build4",
        "1.14.5-1build5",
        "1.14.5-1build6",
        "1.14.6-1",
        "1.14.6-1ubuntu0.1",
        "1.14.6-1ubuntu0.1+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "flatpak",
            "binary_version": "1.16.6-1"
          },
          {
            "binary_name": "flatpak-tests",
            "binary_version": "1.16.6-1"
          },
          {
            "binary_name": "gir1.2-flatpak-1.0",
            "binary_version": "1.16.6-1"
          },
          {
            "binary_name": "libflatpak0",
            "binary_version": "1.16.6-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "flatpak",
        "purl": "pkg:deb/ubuntu/flatpak@1.16.6-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.16.1-2ubuntu1",
        "1.16.1-3ubuntu1",
        "1.16.2-1",
        "1.16.3-1",
        "1.16.3-1build1",
        "1.16.4-1",
        "1.16.4-2",
        "1.16.6-1"
      ]
    }
  ],
  "aliases": [],
  "details": "In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session\u0027s directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation.",
  "id": "UBUNTU-CVE-2026-96808",
  "modified": "2026-09-30T21:39:34Z",
  "published": "2026-09-23T17:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-96808"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-96808"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/flatpak/flatpak/security/advisories/GHSA-qrwq-7qwx-q9rp"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-96808"
  ]
}

CVE-2026-96808 (GCVE-0-2026-96808)

Vulnerability from cvelistv5 – Published: 2026-09-23 16:58 – Updated: 2026-09-23 18:22

Summary

Severity

7.4 (High)


                        
                          CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-23 18:22 UTC

CWE

CWE-61 - UNIX Symbolic Link (Symlink) Following

Assigner

mitre mitre root Scorecard

References

1 reference

URL	Tags
https://github.com/flatpak/flatpak/security/advis…

Impacted products

1 product

Vendor	Product	Version
Flatpak	Flatpak	Affected: 0 , < 1.18.1 (semver) cpe:2.3:a:flatpak:flatpak::::::::

Show details on NVD website

JSON

To clipboard

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  "containers": {
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        "metrics": [
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              "content": {
                "id": "CVE-2026-96808",
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                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
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                "role": "CISA Coordinator",
                "timestamp": "2026-09-23T18:22:36.969505Z",
                "version": "2.0.3"
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          "dateUpdated": "2026-09-23T18:22:46.208Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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      ],
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          "value": "In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session\u0027s directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation."
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    "dateReserved": "2026-09-23T16:58:36.801Z",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
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Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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UBUNTU-CVE-2026-96808 (CVE-2026-96808)

CVE-2026-96808 (GCVE-0-2026-96808)

Tags

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Nomenclature

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