CVE-2026-64139 (GCVE-0-2026-64139)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-07-19 15:40
VLAI
Title
ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow Commit 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16 DACL size overflow") added check_add_overflow() guards that break out of the ACE-building loops in set_posix_acl_entries_dacl() when the accumulated DACL size would wrap past 65535. However, each iteration allocates a struct smb_sid via kmalloc_obj() at the top of the loop and relies on the kfree(sid) call at the end of the loop body (the 'pass_same_sid' label in the first loop, and the explicit kfree at the tail of the second loop) to release it. The newly introduced 'break' statements bypass those kfree() calls, leaking the sid buffer every time an overflow is detected. A malicious or malformed file with enough POSIX ACL entries to trip the overflow check will leak one or more struct smb_sid allocations on every request that touches the file's DACL, providing a trivial kernel memory exhaustion vector. Free sid before breaking out of the loops to plug the leak.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 8d5729350b236896f51379588d9a690b7fafb8db , < 9d378e17c864da08c3a4df41dae92cfa6468b00a (git)
Affected: e1955a94b6f17f4b058afa955a6f187eb3ed7615 , < 519fb0a42ce5d7e46935577309fb282a5f2c6ea3 (git)
Affected: 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43 , < 0e198f09cb2a554c04de0fea4e790f1250a943ca (git)
Affected: ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 , < eced48cb08f07393a5ea770fdd1026452883c3ad (git)
Affected: 299f962c0b02d048fb45d248b4da493d03f3175d , < af92ee994cc7f7e83a41c2025f32257a2f82a7ef (git)
Affected: 41e53a773db6342ac9a689ee5ba635c31744c9f0 (git)
Affected: 6.1.175 , < 6.2 (semver)
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Linux Linux Affected: 6.6.136 , < 6.6.142 (semver)
Affected: 6.12.84 , < 6.12.92 (semver)
Affected: 6.18.25 , < 6.18.34 (semver)
Affected: 7.0.2 , < 7.0.11 (semver)
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{
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          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smbacl.c"
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      "cpeApplicability": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow\n\nCommit 299f962c0b02 (\"ksmbd: use check_add_overflow() to prevent u16\nDACL size overflow\") added check_add_overflow() guards that break out\nof the ACE-building loops in set_posix_acl_entries_dacl() when the\naccumulated DACL size would wrap past 65535.\n\nHowever, each iteration allocates a struct smb_sid via kmalloc_obj()\nat the top of the loop and relies on the kfree(sid) call at the end\nof the loop body (the \u0027pass_same_sid\u0027 label in the first loop, and\nthe explicit kfree at the tail of the second loop) to release it.\nThe newly introduced \u0027break\u0027 statements bypass those kfree() calls,\nleaking the sid buffer every time an overflow is detected.\n\nA malicious or malformed file with enough POSIX ACL entries to trip\nthe overflow check will leak one or more struct smb_sid allocations\non every request that touches the file\u0027s DACL, providing a trivial\nkernel memory exhaustion vector.\n\nFree sid before breaking out of the loops to plug the leak."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-19T15:40:32.459Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/9d378e17c864da08c3a4df41dae92cfa6468b00a"
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          "url": "https://git.kernel.org/stable/c/519fb0a42ce5d7e46935577309fb282a5f2c6ea3"
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          "url": "https://git.kernel.org/stable/c/0e198f09cb2a554c04de0fea4e790f1250a943ca"
        },
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          "url": "https://git.kernel.org/stable/c/eced48cb08f07393a5ea770fdd1026452883c3ad"
        },
        {
          "url": "https://git.kernel.org/stable/c/af92ee994cc7f7e83a41c2025f32257a2f82a7ef"
        }
      ],
      "title": "ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64139",
    "datePublished": "2026-07-19T15:40:32.459Z",
    "dateReserved": "2026-07-19T07:54:57.037Z",
    "dateUpdated": "2026-07-19T15:40:32.459Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-07-21T08:07:25+00:00",
      "cve": "CVE-2026-64139",
      "id": "CVE-2026-64139",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64139.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-07-21T12:58:59Z",
      "cve": "CVE-2026-64139",
      "id": "CVE-2026-64139",
      "initial_release_date": "2026-07-21T12:58:59Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64139",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64139.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.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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