CWE-367
AllowedTime-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.
1068 vulnerabilities reference this CWE, most recent first.
GHSA-FGGM-83VW-5VWQ
Vulnerability from github – Published: 2022-05-24 17:08 – Updated: 2024-04-04 02:47Sander Bos discovered a time of check to time of use (TOCTTOU) vulnerability in apport that allowed a user to cause core files to be written in arbitrary directories.
{
"affected": [],
"aliases": [
"CVE-2019-11482"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-02-08T05:15:00Z",
"severity": "MODERATE"
},
"details": "Sander Bos discovered a time of check to time of use (TOCTTOU) vulnerability in apport that allowed a user to cause core files to be written in arbitrary directories.",
"id": "GHSA-fggm-83vw-5vwq",
"modified": "2024-04-04T02:47:40Z",
"published": "2022-05-24T17:08:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-11482"
},
{
"type": "WEB",
"url": "https://usn.ubuntu.com/usn/usn-4171-1"
},
{
"type": "WEB",
"url": "https://usn.ubuntu.com/usn/usn-4171-2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-FGJC-5272-R725
Vulnerability from github – Published: 2025-07-08 18:31 – Updated: 2025-07-08 18:31Time-of-check time-of-use (toctou) race condition in Windows BitLocker allows an unauthorized attacker to bypass a security feature with a physical attack.
{
"affected": [],
"aliases": [
"CVE-2025-48818"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-08T17:15:46Z",
"severity": "MODERATE"
},
"details": "Time-of-check time-of-use (toctou) race condition in Windows BitLocker allows an unauthorized attacker to bypass a security feature with a physical attack.",
"id": "GHSA-fgjc-5272-r725",
"modified": "2025-07-08T18:31:46Z",
"published": "2025-07-08T18:31:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-48818"
},
{
"type": "WEB",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-48818"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-FGMM-W5CX-VRFW
Vulnerability from github – Published: 2026-05-26 19:30 – Updated: 2026-06-09 11:00Summary
The Pterodactyl Client API has a logic flaw that lets users bypass their assigned limits for database allocations. This happens because the database locking mechanism used in the controllers is totally broken and doesn't actually lock anything.
Details
Inside DatabaseController.php, the code tries to prevent multiple databases from being created at once by calling $server->databases()->lockForUpdate(). In Laravel, this just configures a query builder but never actually sends a command to the database because it’s missing a terminal method like count() or get(). It’s basically a no-op that does nothing.
Since there’s no real lock, multiple requests hitting the endpoint at the exact same time will all see that the database count is under the limit. They all move forward to the DeployServerDatabaseService and successfully create extra resources on the physical host.
Impact
Users are able to create more databases than they are supposed to, potentially also breaking the web interface.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "pterodactyl/panel"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.12.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-35202"
],
"database_specific": {
"cwe_ids": [
"CWE-367",
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-26T19:30:02Z",
"nvd_published_at": "2026-06-02T20:16:35Z",
"severity": "LOW"
},
"details": "### Summary\n\nThe Pterodactyl Client API has a logic flaw that lets users bypass their assigned limits for database allocations. This happens because the database locking mechanism used in the controllers is totally broken and doesn\u0027t actually lock anything.\n\n### Details\n\nInside `DatabaseController.php`, the code tries to prevent multiple databases from being created at once by calling `$server-\u003edatabases()-\u003elockForUpdate()`. In Laravel, this just configures a query builder but never actually sends a command to the database because it\u2019s missing a terminal method like `count()` or `get()`. It\u2019s basically a no-op that does nothing.\n\nSince there\u2019s no real lock, multiple requests hitting the endpoint at the exact same time will all see that the database count is under the limit. They all move forward to the `DeployServerDatabaseService` and successfully create extra resources on the physical host.\n\n### Impact\n\nUsers are able to create more databases than they are supposed to, potentially also breaking the web interface.",
"id": "GHSA-fgmm-w5cx-vrfw",
"modified": "2026-06-09T11:00:09Z",
"published": "2026-05-26T19:30:02Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pterodactyl/panel/security/advisories/GHSA-fgmm-w5cx-vrfw"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35202"
},
{
"type": "PACKAGE",
"url": "https://github.com/pterodactyl/panel"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Pterodactyl has a database resource limit bypass via race condition in Client API"
}
GHSA-FH27-97R5-49GQ
Vulnerability from github – Published: 2022-11-15 12:00 – Updated: 2022-11-18 18:30DMA transactions which are targeted at input buffers used for the software SMI handler used by the IdeBusDxe driver could cause SMRAM corruption through a TOCTOU attack... DMA transactions which are targeted at input buffers used for the software SMI handler used by the IdeBusDxe driver could cause SMRAM corruption through a TOCTOU attack. This issue was discovered by Insyde engineering based on the general description provided by Intel's iSTARE group. Fixed in kernel 5.2: 05.27.25, kernel 5.3: 05.36.25, kernel 5.4: 05.44.25 https://www.insyde.com/security-pledge/SA-2022049
{
"affected": [],
"aliases": [
"CVE-2022-33907"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-11-14T23:15:00Z",
"severity": "MODERATE"
},
"details": "DMA transactions which are targeted at input buffers used for the software SMI handler used by the IdeBusDxe driver could cause SMRAM corruption through a TOCTOU attack... DMA transactions which are targeted at input buffers used for the software SMI handler used by the IdeBusDxe driver could cause SMRAM corruption through a TOCTOU attack. This issue was discovered by Insyde engineering based on the general description provided by Intel\u0027s iSTARE group. Fixed in kernel 5.2: 05.27.25, kernel 5.3: 05.36.25, kernel 5.4: 05.44.25 https://www.insyde.com/security-pledge/SA-2022049",
"id": "GHSA-fh27-97r5-49gq",
"modified": "2022-11-18T18:30:25Z",
"published": "2022-11-15T12:00:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-33907"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-450613.pdf"
},
{
"type": "WEB",
"url": "https://www.insyde.com/security-pledge"
},
{
"type": "WEB",
"url": "https://www.insyde.com/security-pledge/SA-2022049"
}
],
"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-FH7H-QP2R-QP8P
Vulnerability from github – Published: 2024-11-08 15:31 – Updated: 2025-11-04 00:31An attacker with local access the to medical office computer can escalate his Windows user privileges to "NT AUTHORITY\SYSTEM" by exploiting a race condition in the Elefant Update Service during the repair or update process. When using the repair function, the service queries the server for a list of files and their hashes. In addition, instructions to execute binaries to finalize the repair process are included. The executables are executed as "NT AUTHORITY\SYSTEM" after they are copied over to the user writable installation folder (C:\Elefant1). This means that a user can overwrite either "PostESUUpdate.exe" or "Update_OpenJava.exe" in the time frame after the copy and before the execution of the final repair step. The overwritten executable is then executed as "NT AUTHORITY\SYSTEM".
{
"affected": [],
"aliases": [
"CVE-2024-50592"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-11-08T13:15:03Z",
"severity": "HIGH"
},
"details": "An attacker with local access the to medical office computer can \nescalate his Windows user privileges to \"NT AUTHORITY\\SYSTEM\" by \nexploiting a race condition in the Elefant Update Service during the \nrepair or update process.\u00a0When using the repair function, the service queries the server for a \nlist of files and their hashes. In addition, instructions to execute \nbinaries to finalize the repair process are included.\u00a0The executables are executed as \"NT AUTHORITY\\SYSTEM\" after they are \ncopied over to the user writable installation folder (C:\\Elefant1). This\n means that a user can overwrite either \"PostESUUpdate.exe\" or \n\"Update_OpenJava.exe\" in the time frame after the copy and before the \nexecution of the final repair step. The overwritten executable is then executed as \"NT AUTHORITY\\SYSTEM\".",
"id": "GHSA-fh7h-qp2r-qp8p",
"modified": "2025-11-04T00:31:58Z",
"published": "2024-11-08T15:31:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-50592"
},
{
"type": "WEB",
"url": "https://hasomed.de/produkte/elefant"
},
{
"type": "WEB",
"url": "https://r.sec-consult.com/hasomed"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2024/Nov/3"
}
],
"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-FJ2X-XHHP-FV9Q
Vulnerability from github – Published: 2023-02-15 15:30 – Updated: 2023-02-25 03:30An issue was discovered in Insyde InsydeH2O with kernel 5.0 through 5.5. DMA attacks on the PnpSmm shared buffer used by SMM and non-SMM code could cause TOCTOU race-condition issues that could lead to corruption of SMRAM and escalation of privileges. This attack can be mitigated using IOMMU protection for the ACPI runtime memory used for the command buffer. This attack can be mitigated by copying the firmware block services data to SMRAM before checking it.
{
"affected": [],
"aliases": [
"CVE-2022-32469"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-02-15T14:15:00Z",
"severity": "HIGH"
},
"details": "An issue was discovered in Insyde InsydeH2O with kernel 5.0 through 5.5. DMA attacks on the PnpSmm shared buffer used by SMM and non-SMM code could cause TOCTOU race-condition issues that could lead to corruption of SMRAM and escalation of privileges. This attack can be mitigated using IOMMU protection for the ACPI runtime memory used for the command buffer. This attack can be mitigated by copying the firmware block services data to SMRAM before checking it.",
"id": "GHSA-fj2x-xhhp-fv9q",
"modified": "2023-02-25T03:30:16Z",
"published": "2023-02-15T15:30:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-32469"
},
{
"type": "WEB",
"url": "https://www.insyde.com/security-pledge"
},
{
"type": "WEB",
"url": "https://www.insyde.com/security-pledge/SA-2023001"
}
],
"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-FJ7F-JV57-M7JH
Vulnerability from github – Published: 2026-06-09 18:30 – Updated: 2026-06-09 18:30Time-of-check time-of-use (TOCTOU) race condition in Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.
{
"affected": [],
"aliases": [
"CVE-2026-45487"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-09T17:17:24Z",
"severity": "HIGH"
},
"details": "Time-of-check time-of-use (TOCTOU) race condition in Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.",
"id": "GHSA-fj7f-jv57-m7jh",
"modified": "2026-06-09T18:30:50Z",
"published": "2026-06-09T18:30:50Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45487"
},
{
"type": "WEB",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45487"
}
],
"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-FJRM-VJGQ-9RP6
Vulnerability from github – Published: 2026-05-28 12:30 – Updated: 2026-06-10 21:31In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix node_cnt race between extent node destroy and writeback
f2fs_destroy_extent_node() does not set FI_NO_EXTENT before clearing extent nodes. When called from f2fs_drop_inode() with I_SYNC set, concurrent kworker writeback can insert new extent nodes into the same extent tree, racing with the destroy and triggering f2fs_bug_on() in __destroy_extent_node(). The scenario is as follows:
drop inode writeback - iput - f2fs_drop_inode // I_SYNC set - f2fs_destroy_extent_node - __destroy_extent_node - while (node_cnt) { write_lock(&et->lock) __free_extent_tree write_unlock(&et->lock) - __writeback_single_inode - f2fs_outplace_write_data - f2fs_update_read_extent_cache - __update_extent_tree_range // FI_NO_EXTENT not set, // insert new extent node } // node_cnt == 0, exit while - f2fs_bug_on(node_cnt) // node_cnt > 0
Additionally, __update_extent_tree_range() only checks FI_NO_EXTENT for EX_READ type, leaving EX_BLOCK_AGE updates completely unprotected.
This patch set FI_NO_EXTENT under et->lock in __destroy_extent_node(), consistent with other callers (__update_extent_tree_range and __drop_extent_tree) and check FI_NO_EXTENT for both EX_READ and EX_BLOCK_AGE tree.
{
"affected": [],
"aliases": [
"CVE-2026-46194"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-28T10:16:35Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix node_cnt race between extent node destroy and writeback\n\nf2fs_destroy_extent_node() does not set FI_NO_EXTENT before clearing\nextent nodes. When called from f2fs_drop_inode() with I_SYNC set,\nconcurrent kworker writeback can insert new extent nodes into the same\nextent tree, racing with the destroy and triggering f2fs_bug_on() in\n__destroy_extent_node(). The scenario is as follows:\n\ndrop inode writeback\n - iput\n - f2fs_drop_inode // I_SYNC set\n - f2fs_destroy_extent_node\n - __destroy_extent_node\n - while (node_cnt) {\n write_lock(\u0026et-\u003elock)\n __free_extent_tree\n write_unlock(\u0026et-\u003elock)\n - __writeback_single_inode\n - f2fs_outplace_write_data\n - f2fs_update_read_extent_cache\n - __update_extent_tree_range\n // FI_NO_EXTENT not set,\n // insert new extent node\n } // node_cnt == 0, exit while\n - f2fs_bug_on(node_cnt) // node_cnt \u003e 0\n\nAdditionally, __update_extent_tree_range() only checks FI_NO_EXTENT for\nEX_READ type, leaving EX_BLOCK_AGE updates completely unprotected.\n\nThis patch set FI_NO_EXTENT under et-\u003elock in __destroy_extent_node(),\nconsistent with other callers (__update_extent_tree_range and\n__drop_extent_tree) and check FI_NO_EXTENT for both EX_READ and\nEX_BLOCK_AGE tree.",
"id": "GHSA-fjrm-vjgq-9rp6",
"modified": "2026-06-10T21:31:25Z",
"published": "2026-05-28T12:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46194"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0559a0e962aacbb47519e26ee663be04b72dcb92"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/42dd1c91f993431d0b399502479d00e6ad1bca71"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ab1eaf9d5c99042f5b0243bf67a06283a4c0757f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b0e4395870eb3441ddc959f6710b5f6ca61aff26"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ed78aeebef05212ef7dca93bd931e4eff67c113f"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-FP6C-QC7R-8HW9
Vulnerability from github – Published: 2023-10-27 21:30 – Updated: 2023-11-07 21:30A denial of service vulnerability was reported in Lenovo Vantage HardwareScan Plugin version 1.3.0.5 and earlier that could allow a local attacker to delete contents of an arbitrary directory under certain conditions.
{
"affected": [],
"aliases": [
"CVE-2022-3702"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-10-27T20:15:08Z",
"severity": "HIGH"
},
"details": "\nA denial of service vulnerability was reported in Lenovo Vantage HardwareScan Plugin version 1.3.0.5 and earlier that could allow a local attacker to delete contents of an arbitrary directory under certain conditions.\n\n",
"id": "GHSA-fp6c-qc7r-8hw9",
"modified": "2023-11-07T21:30:23Z",
"published": "2023-10-27T21:30:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-3702"
},
{
"type": "WEB",
"url": "https://support.lenovo.com/us/en/product_security/LEN-94532"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-FPC4-498C-4336
Vulnerability from github – Published: 2022-05-24 17:27 – Updated: 2022-05-24 17:27u'Non-secure memory is touched multiple times during TrustZone\u2019s execution and can lead to privilege escalation or memory corruption' in Snapdragon Auto, Snapdragon Compute, Snapdragon Connectivity, Snapdragon Consumer IOT, Snapdragon Industrial IOT, Snapdragon Mobile, Snapdragon Voice & Music, Snapdragon Wired Infrastructure and Networking in APQ8009, APQ8017, APQ8053, APQ8098, IPQ8074, Kamorta, MDM9150, MDM9206, MDM9607, MDM9650, MSM8905, MSM8909, MSM8917, MSM8920, MSM8937, MSM8940, MSM8953, MSM8998, QCA8081, QCS404, QCS605, QCS610, QM215, Rennell, SA415M, SC7180, SDA660, SDA845, SDM429, SDM439, SDM450, SDM630, SDM632, SDM636, SDM660, SDM670, SDM710, SDM845, SDM850, SDX24, SM6150, SM7150, SM8150, SXR1130
{
"affected": [],
"aliases": [
"CVE-2020-3619"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-09-08T10:15:00Z",
"severity": "MODERATE"
},
"details": "u\u0027Non-secure memory is touched multiple times during TrustZone\\u2019s execution and can lead to privilege escalation or memory corruption\u0027 in Snapdragon Auto, Snapdragon Compute, Snapdragon Connectivity, Snapdragon Consumer IOT, Snapdragon Industrial IOT, Snapdragon Mobile, Snapdragon Voice \u0026 Music, Snapdragon Wired Infrastructure and Networking in APQ8009, APQ8017, APQ8053, APQ8098, IPQ8074, Kamorta, MDM9150, MDM9206, MDM9607, MDM9650, MSM8905, MSM8909, MSM8917, MSM8920, MSM8937, MSM8940, MSM8953, MSM8998, QCA8081, QCS404, QCS605, QCS610, QM215, Rennell, SA415M, SC7180, SDA660, SDA845, SDM429, SDM439, SDM450, SDM630, SDM632, SDM636, SDM660, SDM670, SDM710, SDM845, SDM850, SDX24, SM6150, SM7150, SM8150, SXR1130",
"id": "GHSA-fpc4-498c-4336",
"modified": "2022-05-24T17:27:32Z",
"published": "2022-05-24T17:27:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-3619"
},
{
"type": "WEB",
"url": "https://www.qualcomm.com/company/product-security/bulletins/august-2020-bulletin"
},
{
"type": "WEB",
"url": "https://www.qualcomm.com/company/product-security/bulletins/august-2020-security-bulletin"
}
],
"schema_version": "1.4.0",
"severity": []
}
Mitigation
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
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
Limit the interleaving of operations on files from multiple processes.
Mitigation
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
Recheck the resource after the use call to verify that the action was taken appropriately.
Mitigation
Ensure that some environmental locking mechanism can be used to protect resources effectively.
Mitigation
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.