{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "f400e12656ab518be107febfe2315fb1eab5a342"
            },
            {
              "fixed": "b169185d5c672b989985c6c2e38cafab2548ba88"
            },
            {
              "fixed": "c2a126fca820ae74872da28de68dc74d4595dc4b"
            },
            {
              "fixed": "95dadf366c117dcdca78a570e6832071deab1ecd"
            },
            {
              "fixed": "3d2f0cb66c909ea2312cdef465165bb9a3ba2d84"
            },
            {
              "fixed": "bbb2218eb072b0a15dc063929200183bd23c2344"
            },
            {
              "fixed": "d0a3729d464fcf516416a41cf304c0c92126ee03"
            },
            {
              "fixed": "e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe"
            },
            {
              "fixed": "e300eb5002925b29be803d2661af07266cfa267e"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.29"
            },
            {
              "fixed": "5.10.270"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.221"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.188"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.157"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.110"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.52"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90203.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nSquashfs: check block offset is not negative\n\nIf a negative offset is read off disk (for example the offset into the\ndecompressed fragment block), this will cause squashfs_copy_data() to\nperform an out of bounds access.\n\nFix by checking if offset is negative, and returning 0.  This matches\nexisting behaviour where an offset beyond the block returns 0 bytes\ncopied.\n\nTo trigger this out of bounds access requires a crafted Squashfs\nfilesystem and CAP_SYS_ADMIN to mount it.  Unprivileged users will not be\nable to mount such a filesystem, but once mounted, an unprivileged user\ncan trigger the out of bounds access by reading the crafted file with the\nnegative offset.",
  "id": "CVE-2026-90203",
  "modified": "2026-09-20T11:31:06.531647626Z",
  "published": "2026-09-17T16:07:20.180Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3d2f0cb66c909ea2312cdef465165bb9a3ba2d84"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/95dadf366c117dcdca78a570e6832071deab1ecd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b169185d5c672b989985c6c2e38cafab2548ba88"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bbb2218eb072b0a15dc063929200183bd23c2344"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c2a126fca820ae74872da28de68dc74d4595dc4b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d0a3729d464fcf516416a41cf304c0c92126ee03"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e300eb5002925b29be803d2661af07266cfa267e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90203.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90203"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Squashfs: check block offset is not negative"
}