CVE-2026-64317 (GCVE-0-2026-64317)
Vulnerability from cvelistv5
Published
2026-07-25 08:49
Modified
2026-08-17 04:53
Severity ?
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: isofs: bound Rock Ridge symlink components to the SL record get_symlink_chunk() and the SL handling in parse_rock_ridge_inode_internal() walk the variable-length components of a Rock Ridge "SL" (symbolic link) record. Each component is a two-byte header (flags, len) followed by len bytes of text, so it occupies slp->len + 2 bytes. Both loops read slp->len and advance to the next component, and get_symlink_chunk() additionally does memcpy(rpnt, slp->text, slp->len), but neither checks that the component lies within the SL record before dereferencing it. A crafted SL record whose component declares a len that runs past the record (rr->len) therefore triggers an out-of-bounds read of up to 255 bytes. When the record sits at the tail of its backing buffer - for example a small kmalloc()ed continuation block reached through a CE record - the read crosses the allocation; get_symlink_chunk() then copies the out-of-bounds bytes into the symlink body returned to user space by readlink(), disclosing adjacent kernel memory. ISO 9660 images are routinely mounted from untrusted removable media - desktop environments auto-mount them (e.g. via udisks2) without CAP_SYS_ADMIN - so the record contents are attacker-controlled. Reject any component that does not fit in the remaining record bytes before using it. In get_symlink_chunk() return NULL, like the existing output-buffer (plimit) checks, so a malformed record makes readlink() fail with -EIO rather than silently returning a truncated target; in parse_rock_ridge_inode_internal() stop the inode-size walk.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/isofs/rock.c"
          ],
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          "vendor": "Linux",
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              "version": "6.12.96",
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              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nisofs: bound Rock Ridge symlink components to the SL record\n\nget_symlink_chunk() and the SL handling in\nparse_rock_ridge_inode_internal() walk the variable-length components of\na Rock Ridge \"SL\" (symbolic link) record.  Each component is a two-byte\nheader (flags, len) followed by len bytes of text, so it occupies\nslp-\u003elen + 2 bytes.  Both loops read slp-\u003elen and advance to the next\ncomponent, and get_symlink_chunk() additionally does\nmemcpy(rpnt, slp-\u003etext, slp-\u003elen), but neither checks that the component\nlies within the SL record before dereferencing it.\n\nA crafted SL record whose component declares a len that runs past the\nrecord (rr-\u003elen) therefore triggers an out-of-bounds read of up to 255\nbytes.  When the record sits at the tail of its backing buffer - for\nexample a small kmalloc()ed continuation block reached through a CE\nrecord - the read crosses the allocation; get_symlink_chunk() then\ncopies the out-of-bounds bytes into the symlink body returned to user\nspace by readlink(), disclosing adjacent kernel memory.\n\nISO 9660 images are routinely mounted from untrusted removable media -\ndesktop environments auto-mount them (e.g. via udisks2) without\nCAP_SYS_ADMIN - so the record contents are attacker-controlled.\n\nReject any component that does not fit in the remaining record bytes\nbefore using it.  In get_symlink_chunk() return NULL, like the existing\noutput-buffer (plimit) checks, so a malformed record makes readlink()\nfail with -EIO rather than silently returning a truncated target; in\nparse_rock_ridge_inode_internal() stop the inode-size walk."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - An active unprivileged local user can use UDisks2 to mount an attacker-created ISO image and invoke readlink(); ISOFS is not directly mountable through an unprivileged user namespace.\nAC:L - The attacker fully controls the SL component length and CE continuation layout, reliably triggering the out-of-bounds read without a race or an uncontrollable condition.\nPR:L - Direct mounting requires CAP_SYS_ADMIN in the initial user namespace, but common UDisks2 policies permit an active ordinary desktop user to create a loop device and mount the image without administrator authentication.\nUI:N - The local attacker can mount the crafted image and read the symlink themselves, requiring no action by another user.\nS:U - The disclosure and possible crash occur within the host kernel\u0027s existing security authority and do not cross a virtualization or comparable scope boundary.\nC:H - Up to 255 bytes per malformed SL component are copied from beyond a controllably sized kernel allocation into readlink() output; repeated components or attempts can disclose kernel pointers, secrets, and substantial adjacent heap data.\nI:N - The flaw performs an out-of-bounds source read while all destination writes remain bounded to the symlink page, providing no kernel-memory overwrite or control-flow modification primitive.\nA:H - The out-of-bounds memcpy can cross into inaccessible or allocator-guarded memory and cause a kernel oops or panic, and a local attacker can trigger repeated allocations and reads."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:53:17.683Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1015e1c4b2fadd9c09704e24738e46598778c869"
        },
        {
          "url": "https://git.kernel.org/stable/c/36fe7d25dbc40da0c6b1dd4513a4f69ac6164eee"
        },
        {
          "url": "https://git.kernel.org/stable/c/a22cb6bb54dc167047ea9e70d97dfbc2c15649e3"
        },
        {
          "url": "https://git.kernel.org/stable/c/b736b12108fd116c41777628f5a333791604df26"
        },
        {
          "url": "https://git.kernel.org/stable/c/6bf41db09ef935d76fcc84ccf213b42c18de95ee"
        },
        {
          "url": "https://git.kernel.org/stable/c/b5699642640d6cff357638738c5293985cd5a53d"
        },
        {
          "url": "https://git.kernel.org/stable/c/9830725078c8483c6831ec10222ae724806ea36b"
        },
        {
          "url": "https://git.kernel.org/stable/c/5fa1d6a5ec2356d2107dead614437c66fa7138b1"
        }
      ],
      "title": "isofs: bound Rock Ridge symlink components to the SL record",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64317",
    "datePublished": "2026-07-25T08:49:47.067Z",
    "dateReserved": "2026-07-19T15:36:31.779Z",
    "dateUpdated": "2026-08-17T04:53:17.683Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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