Common Weakness Enumeration

CWE-367

Allowed

Time-of-check Time-of-use (TOCTOU) Race Condition

Abstraction: Base · Status: Incomplete

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

1063 vulnerabilities reference this CWE, most recent first.

GHSA-V5C4-WCPJ-X73M

Vulnerability from github – Published: 2026-06-26 23:03 – Updated: 2026-06-26 23:03
VLAI
Summary
Statamic Vulnerable to Server-Side Request Forgery via Glide (DNS rebinding)
Details

Impact

The Glide image proxy's URL validation could be bypassed using DNS rebinding. The remote hostname was validated as publicly routable, but resolved again when the image was actually fetched, so an attacker controlling the hostname's DNS could rebind it to an internal address after validation. This could cause the server to make HTTP requests to internal addresses — including loopback, private network, and cloud metadata endpoints.

This affects sites that pass user-supplied URLs to Glide.

Patches

This has been fixed in 5.73.24 and 6.20.1.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "statamic/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.73.24"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "statamic/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.0.0"
            },
            {
              "fixed": "6.20.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54242"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-26T23:03:28Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nThe Glide image proxy\u0027s URL validation could be bypassed using DNS rebinding. The remote hostname was validated as publicly routable, but resolved again when the image was actually fetched, so an attacker controlling the hostname\u0027s DNS could rebind it to an internal address after validation. This could cause the server to make HTTP requests to internal addresses \u2014 including loopback, private network, and cloud metadata endpoints.\n\nThis affects sites that pass user-supplied URLs to Glide.\n\n\n### Patches\n\nThis has been fixed in 5.73.24 and 6.20.1.",
  "id": "GHSA-v5c4-wcpj-x73m",
  "modified": "2026-06-26T23:03:29Z",
  "published": "2026-06-26T23:03:28Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/statamic/cms/security/advisories/GHSA-v5c4-wcpj-x73m"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/statamic/cms"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Statamic Vulnerable to Server-Side Request Forgery via Glide (DNS rebinding)"
}

GHSA-V666-6W97-PCWM

Vulnerability from github – Published: 2021-08-25 21:01 – Updated: 2021-08-02 21:55
VLAI
Summary
Miner fails to get block template when a cell used as a cell dep has been destroyed.
Details

Impact

The RPC get_block_template fails when a cell has been used as a cell dep and an input in the different transactions.

Say cell C is used as a dep group in the transaction A, and is destroyed in the transaction B.

The node adds transaction A first, then B into the transaction pool. They are both valid. But when generating the block template, if the fee rate of B is higher, it comes before A, which will invalidate A. Currently the RPC get_block_template will fail instead of dropping A.

Patch

First, the get_block_template should not fail but dropping the conflict transactions.

Then we can propose solution to this issue. Here is an example. When a transaction is added to the pool, the pool must consider it depending on all the transactions which dep cell (direct or indirect via dep group) has been destroyed in this transaction. Because future transactions using the destroyed cells as dep will be rejected, the spending transaction only need to wait for all the existing dep transactions on chain.

Workaround

  1. Submit transaction B when A is already on chain.
  2. Let B depend on A explicitly, there are several solutions:
    • a. Add any output cell on A as a dep cell or input in B.
    • b. Merge A and B. CKB allows using the same cell as both dep and input in the same transaction.
  3. Ensure the fee rate of B is less than A so A always has higher priority.
Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "ckb"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.40.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-08-02T21:55:20Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\n\nThe RPC `get_block_template` fails when a cell has been used as a cell dep and an input in the different transactions.\n\nSay cell C is used as a dep group in the transaction A, and is destroyed in the transaction B.\n\nThe node adds transaction A first, then B into the transaction pool. They are both valid. But when generating the block template, if the fee rate of B is higher, it comes before A, which will invalidate A. Currently the RPC `get_block_template` will fail instead of dropping A.\n\n### Patch\n\nFirst, the `get_block_template` should not fail but dropping the conflict transactions.\n\nThen we can propose solution to this issue. Here is an example. When a transaction is added to the pool, the pool must consider it depending on all the transactions which dep cell (direct or indirect via dep group) has been destroyed in this transaction. Because future transactions using the destroyed cells as dep will be rejected, the spending transaction only need to wait for all the existing dep transactions on chain.\n\n### Workaround\n\n1. Submit transaction B when A is already on chain.\n2. Let B depend on A explicitly, there are several solutions:\n    * a. Add any output cell on A as a dep cell or input in B.\n    * b. Merge A and B. CKB allows using the same cell as both dep and input in the same transaction.\n3. Ensure the fee rate of B is less than A so A always has higher priority.\n",
  "id": "GHSA-v666-6w97-pcwm",
  "modified": "2021-08-02T21:55:20Z",
  "published": "2021-08-25T21:01:21Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nervosnetwork/ckb/security/advisories/GHSA-v666-6w97-pcwm"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2021-0107.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [],
  "summary": "Miner fails to get block template when a cell used as a cell dep has been destroyed."
}

GHSA-V6GP-395W-JVCW

Vulnerability from github – Published: 2023-08-20 09:30 – Updated: 2024-04-04 07:03
VLAI
Details

Unity Parsec before 8 has a TOCTOU race condition that permits local attackers to escalate privileges to SYSTEM if Parsec was installed in "Per User" mode. The application intentionally launches DLLs from a user-owned directory but intended to always perform integrity verification of those DLLs.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-37250"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-08-20T08:15:09Z",
    "severity": "HIGH"
  },
  "details": "Unity Parsec before 8 has a TOCTOU race condition that permits local attackers to escalate privileges to SYSTEM if Parsec was installed in \"Per User\" mode. The application intentionally launches DLLs from a user-owned directory but intended to always perform integrity verification of those DLLs.",
  "id": "GHSA-v6gp-395w-jvcw",
  "modified": "2024-04-04T07:03:50Z",
  "published": "2023-08-20T09:30:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-37250"
    },
    {
      "type": "WEB",
      "url": "https://support.parsec.app/hc/en-us/articles/18311425588237-CVE-2023-37250"
    },
    {
      "type": "WEB",
      "url": "https://unity3d.com"
    },
    {
      "type": "WEB",
      "url": "https://www.kb.cert.org/vuls/id/287122"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-V6HW-6VC6-J7HX

Vulnerability from github – Published: 2022-05-19 00:00 – Updated: 2022-05-27 00:00
VLAI
Details

A Time of Check Time of Use (TOCTOU) vulnerability was reported in IMController, a software component of Lenovo System Interface Foundation, prior to version 1.1.20.3that could allow a local attacker to elevate privileges.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2021-3969"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-05-18T16:15:00Z",
    "severity": "HIGH"
  },
  "details": "A Time of Check Time of Use (TOCTOU) vulnerability was reported in IMController, a software component of Lenovo System Interface Foundation, prior to version 1.1.20.3that could allow a local attacker to elevate privileges.",
  "id": "GHSA-v6hw-6vc6-j7hx",
  "modified": "2022-05-27T00:00:23Z",
  "published": "2022-05-19T00:00:25Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-3969"
    },
    {
      "type": "WEB",
      "url": "https://support.lenovo.com/us/en/product_security/LEN-75210"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-V757-7WM5-J6J9

Vulnerability from github – Published: 2024-05-03 03:30 – Updated: 2024-05-03 03:30
VLAI
Details

Tesla Model 3 Gateway Firmware Signature Validation Bypass Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected Tesla Model 3 vehicles. An attacker must first obtain the ability to execute privileged code on the Tesla infotainment system in order to exploit this vulnerability.

The specific flaw exists within the handling of firmware updates. The issue results from improper error-handling during the update process. An attacker can leverage this vulnerability to execute code in the context of Tesla's Gateway ECU. Was ZDI-CAN-20734.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-32156"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-05-03T02:15:20Z",
    "severity": "CRITICAL"
  },
  "details": "Tesla Model 3 Gateway Firmware Signature Validation Bypass Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected Tesla Model 3 vehicles. An attacker must first obtain the ability to execute privileged code on the Tesla infotainment system in order to exploit this vulnerability.\n\nThe specific flaw exists within the handling of firmware updates. The issue results from improper error-handling during the update process. An attacker can leverage this vulnerability to execute code in the context of Tesla\u0027s Gateway ECU. Was ZDI-CAN-20734.",
  "id": "GHSA-v757-7wm5-j6j9",
  "modified": "2024-05-03T03:30:50Z",
  "published": "2024-05-03T03:30:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-32156"
    },
    {
      "type": "WEB",
      "url": "https://www.zerodayinitiative.com/advisories/ZDI-23-972"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-V8VQ-X955-WQ3Q

Vulnerability from github – Published: 2023-08-07 06:30 – Updated: 2024-04-04 06:34
VLAI
Details

In thermal, there is a possible use after free due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS07648734; Issue ID: ALPS07648735.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-20788"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-08-07T04:15:13Z",
    "severity": "MODERATE"
  },
  "details": "In thermal, there is a possible use after free due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS07648734; Issue ID: ALPS07648735.",
  "id": "GHSA-v8vq-x955-wq3q",
  "modified": "2024-04-04T06:34:53Z",
  "published": "2023-08-07T06:30:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-20788"
    },
    {
      "type": "WEB",
      "url": "https://corp.mediatek.com/product-security-bulletin/August-2023"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-V9HV-WGMV-7QJ2

Vulnerability from github – Published: 2025-05-26 15:30 – Updated: 2025-05-26 15:30
VLAI
Details

Screen version 5.0.0 and older version 4 releases have a TOCTOU race potentially allowing to send SIGHUP, SIGCONT to privileged processes when installed setuid-root.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-46805"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-05-26T14:15:20Z",
    "severity": "MODERATE"
  },
  "details": "Screen version 5.0.0 and older version 4 releases have  a TOCTOU race potentially allowing to send SIGHUP, SIGCONT to privileged processes when installed setuid-root.",
  "id": "GHSA-v9hv-wgmv-7qj2",
  "modified": "2025-05-26T15:30:34Z",
  "published": "2025-05-26T15:30:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-46805"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.suse.com/show_bug.cgi?id=CVE-2025-46805"
    },
    {
      "type": "WEB",
      "url": "https://www.openwall.com/lists/oss-security/2025/05/12/1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-V9Q2-JXCM-RM4C

Vulnerability from github – Published: 2022-11-03 12:00 – Updated: 2025-05-05 15:30
VLAI
Details

Alpine before 2.25 allows remote attackers to cause a denial of service (daemon crash) when LIST or LSUB is sent before STARTTLS.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2021-46853"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-11-03T06:15:00Z",
    "severity": "MODERATE"
  },
  "details": "Alpine before 2.25 allows remote attackers to cause a denial of service (daemon crash) when LIST or LSUB is sent before STARTTLS.",
  "id": "GHSA-v9q2-jxcm-rm4c",
  "modified": "2025-05-05T15:30:38Z",
  "published": "2022-11-03T12:00:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-46853"
    },
    {
      "type": "WEB",
      "url": "https://bugs.gentoo.org/807613"
    },
    {
      "type": "WEB",
      "url": "https://nostarttls.secvuln.info"
    },
    {
      "type": "WEB",
      "url": "https://security.gentoo.org/glsa/202301-07"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-VF2Q-W6VQ-3HQ8

Vulnerability from github – Published: 2026-07-10 21:32 – Updated: 2026-07-13 21:31
VLAI
Details

Kernel software installed and running inside a Host VM may post improper commands to the GPU Firmware to trigger a memory write outside the permitted range of memory for the host kernel.

A TOCTOU bug existed where a malicious driver could modify values in memory after firmware validation but before use.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-45203"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-10T21:16:54Z",
    "severity": "HIGH"
  },
  "details": "Kernel software installed and running inside a Host VM may post improper commands to the GPU Firmware to trigger a memory write outside the permitted range of memory for the host kernel.\n\n\n\nA TOCTOU bug existed where a malicious driver could modify values in memory after firmware validation but before use.",
  "id": "GHSA-vf2q-w6vq-3hq8",
  "modified": "2026-07-13T21:31:17Z",
  "published": "2026-07-10T21:32:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45203"
    },
    {
      "type": "WEB",
      "url": "https://www.imaginationtech.com/gpu-driver-vulnerabilities"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-VF87-345H-9QHX

Vulnerability from github – Published: 2026-04-22 18:31 – Updated: 2026-07-06 20:16
VLAI
Summary
Duplicate Advisory: uutils coreutils has a Time-of-check Time-of-use (TOCTOU) Race Condition
Details

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-mj6p-44ch-cq69. This link is maintained to preserve external references.

Original Description

The mkdir utility in uutils coreutils incorrectly applies permissions when using the -m flag by creating a directory with umask-derived permissions (typically 0755) before subsequently changing them to the requested mode via a separate chmod system call. In multi-user environments, this introduces a brief window where a directory intended to be private is accessible to other users, potentially leading to unauthorized data access.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "coreutils"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.6.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-29T23:22:16Z",
    "nvd_published_at": "2026-04-22T17:16:37Z",
    "severity": "LOW"
  },
  "details": "### Duplicate Advisory\nThis advisory has been withdrawn because it is a duplicate of GHSA-mj6p-44ch-cq69. This link is maintained to preserve external references.\n\n### Original Description\nThe mkdir utility in uutils coreutils incorrectly applies permissions when using the -m flag by creating a directory with umask-derived permissions (typically 0755) before subsequently changing them to the requested mode via a separate chmod system call. In multi-user environments, this introduces a brief window where a directory intended to be private is accessible to other users, potentially leading to unauthorized data access.",
  "id": "GHSA-vf87-345h-9qhx",
  "modified": "2026-07-06T20:16:07Z",
  "published": "2026-04-22T18:31:45Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35353"
    },
    {
      "type": "WEB",
      "url": "https://github.com/uutils/coreutils/pull/10036"
    },
    {
      "type": "WEB",
      "url": "https://github.com/uutils/coreutils/commit/037b9583bc03d814e8516df54ebcda6f681fe1f8"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/uutils/coreutils"
    },
    {
      "type": "WEB",
      "url": "https://github.com/uutils/coreutils/releases/tag/0.6.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Duplicate Advisory: uutils coreutils has a Time-of-check Time-of-use (TOCTOU) Race Condition",
  "withdrawn": "2026-07-06T20:16:07Z"
}

Mitigation
Implementation

The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.

Mitigation
Implementation

When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.

Mitigation
Architecture and Design

Limit the interleaving of operations on files from multiple processes.

Mitigation
Implementation Architecture and Design

If you cannot perform operations atomically and you must share access to the resource between multiple processes or threads, then try to limit the amount of time (CPU cycles) between the check and use of the resource. This will not fix the problem, but it could make it more difficult for an attack to succeed.

Mitigation
Implementation

Recheck the resource after the use call to verify that the action was taken appropriately.

Mitigation
Architecture and Design

Ensure that some environmental locking mechanism can be used to protect resources effectively.

Mitigation
Implementation

Ensure that locking occurs before the check, as opposed to afterwards, such that the resource, as checked, is the same as it is when in use.

CAPEC-27: Leveraging Race Conditions via Symbolic Links

This attack leverages the use of symbolic links (Symlinks) in order to write to sensitive files. An attacker can create a Symlink link to a target file not otherwise accessible to them. When the privileged program tries to create a temporary file with the same name as the Symlink link, it will actually write to the target file pointed to by the attackers' Symlink link. If the attacker can insert malicious content in the temporary file they will be writing to the sensitive file by using the Symlink. The race occurs because the system checks if the temporary file exists, then creates the file. The attacker would typically create the Symlink during the interval between the check and the creation of the temporary file.

CAPEC-29: Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions

This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. A typical example is file access. The adversary can leverage a file access race condition by "running the race", meaning that they would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the adversary could replace or modify the file, causing the application to behave unexpectedly.