CVE-2026-68099 (GCVE-0-2026-68099)

Vulnerability from cvelistv5 – Published: 2026-08-10 11:58 – Updated: 2026-08-17 04:58
VLAI
Title
ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL check_add_overflow() unconditionally writes the truncated sum into *d even on overflow, per its contract in include/linux/overflow.h. The four check_add_overflow() guards in set_posix_acl_entries_dacl() and set_ntacl_dacl() break out of the ACE-building loops on overflow, but the truncated *size is then consumed downstream at the end of set_ntacl_dacl(): pndacl->size = cpu_to_le16(le16_to_cpu(pndacl->size) + size); This produces an on-wire NT ACL whose pndacl->size under-reports the bytes actually written by the preceding fill_ace_for_sid()/memcpy() calls, yielding a malformed ACL that can trigger out-of-bounds reads when re-parsed by clients or ksmbd itself. Restore *size to its pre-addition value on each overflow branch (via `*size -= ace_sz` / `size -= nt_ace_size`) so that after the break, *size once again holds the cumulative size of the successfully-written ACEs. The committed ACL is then truncated-but-self-consistent rather than malformed. The ksmbd DACL builders are the only check_add_overflow() sites found where an overflow path breaks out of a loop and the destination value is consumed afterward. The other nearby break-style cases either return -EINVAL on overflow (transport_ipc.c) or break without consuming the overflowed destination value afterward (buildid.c).
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 8d5729350b236896f51379588d9a690b7fafb8db , < f4fcd0c1a243d449307b887fafee23921e9db5ab (git)
Affected: e1955a94b6f17f4b058afa955a6f187eb3ed7615 , < 0bf38372821b1526f31538a7d9811844c55c7f38 (git)
Affected: 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43 , < 847ecd4eb3c117c3d2f13f1e7ab506543aad8183 (git)
Affected: 299f962c0b02d048fb45d248b4da493d03f3175d , < bc90144ce8bb7fcf05ad9417c7adb4e9509d9e13 (git)
Affected: 299f962c0b02d048fb45d248b4da493d03f3175d , < bbf0a8e931204ecdab494a88d43b0a24a04285c5 (git)
Affected: 41e53a773db6342ac9a689ee5ba635c31744c9f0 (git)
Affected: ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 (git)
Affected: 6.6.136 , < 6.6.148 (semver)
Affected: 6.12.84 , < 6.12.101 (semver)
Affected: 6.18.25 , < 6.18.42 (semver)
Affected: 6.1.175 , < 6.2 (semver)
Affected: 7.0.2 , < 7.1 (semver)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 6.6.148 , ≤ 6.6.* (semver)
Unaffected: 6.12.101 , ≤ 6.12.* (semver)
Unaffected: 6.18.42 , ≤ 6.18.* (semver)
Unaffected: 7.1.6 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL\n\ncheck_add_overflow() unconditionally writes the truncated sum into *d\neven on overflow, per its contract in include/linux/overflow.h.\nThe four check_add_overflow() guards in set_posix_acl_entries_dacl()\nand set_ntacl_dacl() break out of the ACE-building loops on overflow,\nbut the truncated *size is then consumed downstream at the end of\nset_ntacl_dacl():\n\n    pndacl-\u003esize = cpu_to_le16(le16_to_cpu(pndacl-\u003esize) + size);\n\nThis produces an on-wire NT ACL whose pndacl-\u003esize under-reports the\nbytes actually written by the preceding fill_ace_for_sid()/memcpy()\ncalls, yielding a malformed ACL that can trigger out-of-bounds reads\nwhen re-parsed by clients or ksmbd itself.\n\nRestore *size to its pre-addition value on each overflow branch (via\n`*size -= ace_sz` / `size -= nt_ace_size`) so that after the break,\n*size once again holds the cumulative size of the successfully-written\nACEs. The committed ACL is then truncated-but-self-consistent rather\nthan malformed.\n\nThe ksmbd DACL builders are the only check_add_overflow() sites found\nwhere an overflow path breaks out of a loop and the destination value\nis consumed afterward. The other nearby break-style cases either\nreturn -EINVAL on overflow (transport_ipc.c) or break without\nconsuming the overflowed destination value afterward (buildid.c)."
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      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:58:48.112Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/f4fcd0c1a243d449307b887fafee23921e9db5ab"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68099",
    "datePublished": "2026-08-10T11:58:13.940Z",
    "dateReserved": "2026-07-30T09:28:09.368Z",
    "dateUpdated": "2026-08-17T04:58:48.112Z",
    "state": "PUBLISHED"
  },
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The committed ACL is then truncated-but-self-consistent rather\\nthan malformed.\\n\\nThe ksmbd DACL builders are the only check_add_overflow() sites found\\nwhere an overflow path breaks out of a loop and the destination value\\nis consumed afterward. The other nearby break-style cases either\\nreturn -EINVAL on overflow (transport_ipc.c) or break without\\nconsuming the overflowed destination value afterward (buildid.c).\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/smb/server/smbacl.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"8d5729350b236896f51379588d9a690b7fafb8db\",\"lessThan\":\"f4fcd0c1a243d449307b887fafee23921e9db5ab\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"e1955a94b6f17f4b058afa955a6f187eb3ed7615\",\"lessThan\":\"0bf38372821b1526f31538a7d9811844c55c7f38\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43\",\"lessThan\":\"847ecd4eb3c117c3d2f13f1e7ab506543aad8183\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"299f962c0b02d048fb45d248b4da493d03f3175d\",\"lessThan\":\"bc90144ce8bb7fcf05ad9417c7adb4e9509d9e13\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"299f962c0b02d048fb45d248b4da493d03f3175d\",\"lessThan\":\"bbf0a8e931204ecdab494a88d43b0a24a04285c5\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"41e53a773db6342ac9a689ee5ba635c31744c9f0\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6.6.136\",\"lessThan\":\"6.6.148\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"6.12.84\",\"lessThan\":\"6.12.101\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"6.18.25\",\"lessThan\":\"6.18.42\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"6.1.175\",\"lessThan\":\"6.2\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"7.0.2\",\"lessThan\":\"7.1\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/smb/server/smbacl.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"7.1\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"7.1\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.148\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.101\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.42\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.6\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0bf38372821b1526f31538a7d9811844c55c7f38\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/847ecd4eb3c117c3d2f13f1e7ab506543aad8183\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bbf0a8e931204ecdab494a88d43b0a24a04285c5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bc90144ce8bb7fcf05ad9417c7adb4e9509d9e13\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f4fcd0c1a243d449307b887fafee23921e9db5ab\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-08-18T10:48:59+00:00",
      "cve": "CVE-2026-68099",
      "id": "CVE-2026-68099",
      "initial_release_date": "2026-08-10T00:00:00+00:00",
      "product_status:known_not_affected": "98",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68099.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-11T23:48:26Z",
      "cve": "CVE-2026-68099",
      "id": "CVE-2026-68099",
      "initial_release_date": "2026-08-11T23:48:26Z",
      "product_status:known_affected": "99",
      "product_status:known_not_affected": "197",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-68099",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68099.json",
      "version": "2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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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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Detection rules are retrieved from Rulezet.