Flatpak: flatpak: unprivileged active user can bypass anti-downgrade checks for system apps/runtimes

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-96281",
    "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
    "assignerShortName": "redhat",
    "dateUpdated": "2026-09-27T21:16:34.274Z",
    "dateReserved": "2026-09-22T20:43:45.571Z",
    "datePublished": "2026-09-27T21:00:17.262Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
        "shortName": "redhat",
        "dateUpdated": "2026-09-27T21:16:34.274Z"
      },
      "datePublic": "2026-08-11T00:00:00.000Z",
      "title": "Flatpak: flatpak: unprivileged active user can bypass anti-downgrade checks for system apps/runtimes",
      "descriptions": [
        {
          "lang": "en",
          "value": "On a multi-user system, a user with an active local login session could downgrade a system-wide Flatpak app to an older version by removing the app's remote ref via the unprivileged system-helper RemoveLocalRef method, causing the anti-downgrade check to fail to find a reference date. A malicious local user could use this to expose other users of the same system to an app version with unfixed vulnerabilities."
        }
      ],
      "affected": [
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 10",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "flatpak",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:10"
          ],
          "defaultStatus": "affected"
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 7",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "flatpak",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:7"
          ],
          "defaultStatus": "affected"
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 8",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "flatpak",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:8"
          ],
          "defaultStatus": "affected"
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 9",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "flatpak",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:9"
          ],
          "defaultStatus": "affected"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "Improper Access Control",
              "cweId": "CWE-284",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://access.redhat.com/security/cve/CVE-2026-96281",
          "tags": [
            "vdb-entry",
            "x_refsource_REDHAT"
          ]
        },
        {
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2539421",
          "name": "RHBZ#2539421",
          "tags": [
            "issue-tracking",
            "x_refsource_REDHAT"
          ]
        },
        {
          "url": "https://github.com/flatpak/flatpak/security/advisories/GHSA-q4gr-vc25-57m5"
        }
      ],
      "metrics": [
        {},
        {
          "format": "CVSS",
          "cvssV3_1": {
            "version": "3.1",
            "vectorString": "CVSS:3.1/AV:P/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H",
            "attackVector": "PHYSICAL",
            "attackComplexity": "HIGH",
            "privilegesRequired": "LOW",
            "userInteraction": "REQUIRED",
            "scope": "UNCHANGED",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "availabilityImpact": "HIGH",
            "baseScore": 6.2,
            "baseSeverity": "MEDIUM"
          }
        }
      ],
      "workarounds": [
        {
          "lang": "en",
          "value": "Ensure that Flatpak apps installed system-wide are fully updated before running them."
        }
      ],
      "timeline": [
        {
          "time": "2026-08-11T00:00:00.000Z",
          "lang": "en",
          "value": "Reported to Red Hat."
        },
        {
          "time": "2026-08-11T00:00:00.000Z",
          "lang": "en",
          "value": "Made public."
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Upstream acknowledges Vivek Parikh (BreachX Zero Day Labs) as the original reporter."
        }
      ]
    }
  }
}