Common Weakness Enumeration

CWE-122

Allowed

Heap-based Buffer Overflow

Abstraction: Variant · Status: Draft

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

6285 vulnerabilities reference this CWE, most recent first.

GHSA-FQV7-FHQ2-929V

Vulnerability from github – Published: 2024-05-01 21:30 – Updated: 2024-07-03 18:38
VLAI
Details

libmodbus v3.1.10 has a heap-based buffer overflow vulnerability in read_io_status function in src/modbus.c.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-26793"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-05-01T19:15:21Z",
    "severity": "CRITICAL"
  },
  "details": "libmodbus v3.1.10 has a heap-based buffer overflow vulnerability in read_io_status function in src/modbus.c.",
  "id": "GHSA-fqv7-fhq2-929v",
  "modified": "2024-07-03T18:38:21Z",
  "published": "2024-05-01T21:30:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-26793"
    },
    {
      "type": "WEB",
      "url": "https://github.com/stephane/libmodbus/issues/683"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-FQW7-JXVW-P9PW

Vulnerability from github – Published: 2026-02-03 21:31 – Updated: 2026-03-16 18:32
VLAI
Details

Heap-based Buffer Overflow vulnerability in TP-Link Archer AX53 v1.0 (tmpserver modules) allows authenticated adjacent attackers to cause a segmentation fault or potentially execute arbitrary code via a specially crafted network packet whose length exceeds the maximum expected value.This issue affects Archer AX53 v1.0: through 1.3.1 Build 20241120.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-58455"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-02-03T19:16:13Z",
    "severity": "HIGH"
  },
  "details": "Heap-based Buffer Overflow vulnerability in TP-Link Archer AX53 v1.0 (tmpserver modules) allows authenticated adjacent attackers to cause a segmentation fault or potentially execute arbitrary code via a specially crafted network packet whose length exceeds the maximum expected value.This issue affects Archer AX53 v1.0: through 1.3.1 Build 20241120.",
  "id": "GHSA-fqw7-jxvw-p9pw",
  "modified": "2026-03-16T18:32:02Z",
  "published": "2026-02-03T21:31:51Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-58455"
    },
    {
      "type": "WEB",
      "url": "https://talosintelligence.com/vulnerability_reports"
    },
    {
      "type": "WEB",
      "url": "https://www.talosintelligence.com/vulnerability_reports/TALOS-2025-2289"
    },
    {
      "type": "WEB",
      "url": "https://www.tp-link.com/en/support/download/archer-ax53/v1/#Firmware"
    },
    {
      "type": "WEB",
      "url": "https://www.tp-link.com/my/support/download/archer-ax53/v1/#Firmware"
    },
    {
      "type": "WEB",
      "url": "https://www.tp-link.com/us/support/faq/4943"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:A/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/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-FR33-MQ6Q-MX98

Vulnerability from github – Published: 2024-10-08 18:33 – Updated: 2024-10-08 18:33
VLAI
Details

Windows Routing and Remote Access Service (RRAS) Remote Code Execution Vulnerability

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2024-43593"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-10-08T18:15:27Z",
    "severity": "HIGH"
  },
  "details": "Windows Routing and Remote Access Service (RRAS) Remote Code Execution Vulnerability",
  "id": "GHSA-fr33-mq6q-mx98",
  "modified": "2024-10-08T18:33:17Z",
  "published": "2024-10-08T18:33:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-43593"
    },
    {
      "type": "WEB",
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-43593"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-FR9W-862R-X425

Vulnerability from github – Published: 2026-07-27 18:31 – Updated: 2026-07-27 21:31
VLAI
Details

LibRaw 0.21 is vulnerable to Buffer Overflow in the stretch() function (src/libraw_cxx.cpp) and fuji_rotate() function (src/decoders/fuji.cpp).

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-51235"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-27T18:16:56Z",
    "severity": "HIGH"
  },
  "details": "LibRaw 0.21 is vulnerable to Buffer Overflow in the stretch() function (src/libraw_cxx.cpp) and fuji_rotate() function (src/decoders/fuji.cpp).",
  "id": "GHSA-fr9w-862r-x425",
  "modified": "2026-07-27T21:31:21Z",
  "published": "2026-07-27T18:31:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-51235"
    },
    {
      "type": "WEB",
      "url": "https://github.com/programmervuln/cveadvisory-/blob/main/CVE-2026-51235"
    },
    {
      "type": "WEB",
      "url": "http://libraw.com"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-FRF6-886P-P44M

Vulnerability from github – Published: 2025-03-11 18:32 – Updated: 2025-03-11 18:32
VLAI
Details

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-24057"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-03-11T17:16:28Z",
    "severity": "HIGH"
  },
  "details": "Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.",
  "id": "GHSA-frf6-886p-p44m",
  "modified": "2025-03-11T18:32:17Z",
  "published": "2025-03-11T18:32:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-24057"
    },
    {
      "type": "WEB",
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-24057"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-FRM4-P95X-PR4G

Vulnerability from github – Published: 2025-11-25 18:32 – Updated: 2025-11-28 18:30
VLAI
Details

A Heap-based Buffer Overflow vulnerability is present in Ashlar-Vellum Cobalt, Xenon, Argon, Lithium, and Cobalt Share versions 12.6.1204.207 and prior that could allow an attacker to disclose information or execute arbitrary code.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-65085"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-11-25T18:15:54Z",
    "severity": "HIGH"
  },
  "details": "A Heap-based Buffer Overflow vulnerability is present in Ashlar-Vellum Cobalt, Xenon, Argon, Lithium, and Cobalt Share versions 12.6.1204.207 and prior that could allow an attacker to disclose information or execute arbitrary code.",
  "id": "GHSA-frm4-p95x-pr4g",
  "modified": "2025-11-28T18:30:22Z",
  "published": "2025-11-25T18:32:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-65085"
    },
    {
      "type": "WEB",
      "url": "https://www.cisa.gov/news-events/ics-advisories/icsa-25-329-01"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/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-FV37-H825-2CJ8

Vulnerability from github – Published: 2026-09-08 18:32 – Updated: 2026-09-08 18:32
VLAI
Details

Heap-based buffer overflow in Windows Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-69563"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-08T18:19:25Z",
    "severity": "HIGH"
  },
  "details": "Heap-based buffer overflow in Windows Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.",
  "id": "GHSA-fv37-h825-2cj8",
  "modified": "2026-09-08T18:32:45Z",
  "published": "2026-09-08T18:32:45Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-69563"
    },
    {
      "type": "WEB",
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69563"
    }
  ],
  "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-FV49-MRX3-2JVJ

Vulnerability from github – Published: 2026-01-13 18:31 – Updated: 2026-07-30 06:32
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

ethtool: Avoid overflowing userspace buffer on stats query

The ethtool -S command operates across three ioctl calls: ETHTOOL_GSSET_INFO for the size, ETHTOOL_GSTRINGS for the names, and ETHTOOL_GSTATS for the values.

If the number of stats changes between these calls (e.g., due to device reconfiguration), userspace's buffer allocation will be incorrect, potentially leading to buffer overflow.

Drivers are generally expected to maintain stable stat counts, but some drivers (e.g., mlx5, bnx2x, bna, ksz884x) use dynamic counters, making this scenario possible.

Some drivers try to handle this internally: - bnad_get_ethtool_stats() returns early in case stats.n_stats is not equal to the driver's stats count. - micrel/ksz884x also makes sure not to write anything beyond stats.n_stats and overflow the buffer.

However, both use stats.n_stats which is already assigned with the value returned from get_sset_count(), hence won't solve the issue described here.

Change ethtool_get_strings(), ethtool_get_stats(), ethtool_get_phy_stats() to not return anything in case of a mismatch between userspace's size and get_sset_size(), to prevent buffer overflow. The returned n_stats value will be equal to zero, to reflect that nothing has been returned.

This could result in one of two cases when using upstream ethtool, depending on when the size change is detected: 1. When detected in ethtool_get_strings(): # ethtool -S eth2 no stats available

  1. When detected in get stats, all stats will be reported as zero.

Both cases are presumably transient, and a subsequent ethtool call should succeed.

Other than the overflow avoidance, these two cases are very evident (no output/cleared stats), which is arguably better than presenting incorrect/shifted stats. I also considered returning an error instead of a "silent" response, but that seems more destructive towards userspace apps.

Notes: - This patch does not claim to fix the inherent race, it only makes sure that we do not overflow the userspace buffer, and makes for a more predictable behavior.

  • RTNL lock is held during each ioctl, the race window exists between the separate ioctl calls when the lock is released.

  • Userspace ethtool always fills stats.n_stats, but it is likely that these stats ioctls are implemented in other userspace applications which might not fill it. The added code checks that it's not zero, to prevent any regressions.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-68795"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-01-13T16:16:01Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nethtool: Avoid overflowing userspace buffer on stats query\n\nThe ethtool -S command operates across three ioctl calls:\nETHTOOL_GSSET_INFO for the size, ETHTOOL_GSTRINGS for the names, and\nETHTOOL_GSTATS for the values.\n\nIf the number of stats changes between these calls (e.g., due to device\nreconfiguration), userspace\u0027s buffer allocation will be incorrect,\npotentially leading to buffer overflow.\n\nDrivers are generally expected to maintain stable stat counts, but some\ndrivers (e.g., mlx5, bnx2x, bna, ksz884x) use dynamic counters, making\nthis scenario possible.\n\nSome drivers try to handle this internally:\n- bnad_get_ethtool_stats() returns early in case stats.n_stats is not\n  equal to the driver\u0027s stats count.\n- micrel/ksz884x also makes sure not to write anything beyond\n  stats.n_stats and overflow the buffer.\n\nHowever, both use stats.n_stats which is already assigned with the value\nreturned from get_sset_count(), hence won\u0027t solve the issue described\nhere.\n\nChange ethtool_get_strings(), ethtool_get_stats(),\nethtool_get_phy_stats() to not return anything in case of a mismatch\nbetween userspace\u0027s size and get_sset_size(), to prevent buffer\noverflow.\nThe returned n_stats value will be equal to zero, to reflect that\nnothing has been returned.\n\nThis could result in one of two cases when using upstream ethtool,\ndepending on when the size change is detected:\n1. When detected in ethtool_get_strings():\n    # ethtool -S eth2\n    no stats available\n\n2. When detected in get stats, all stats will be reported as zero.\n\nBoth cases are presumably transient, and a subsequent ethtool call\nshould succeed.\n\nOther than the overflow avoidance, these two cases are very evident (no\noutput/cleared stats), which is arguably better than presenting\nincorrect/shifted stats.\nI also considered returning an error instead of a \"silent\" response, but\nthat seems more destructive towards userspace apps.\n\nNotes:\n- This patch does not claim to fix the inherent race, it only makes sure\n  that we do not overflow the userspace buffer, and makes for a more\n  predictable behavior.\n\n- RTNL lock is held during each ioctl, the race window exists between\n  the separate ioctl calls when the lock is released.\n\n- Userspace ethtool always fills stats.n_stats, but it is likely that\n  these stats ioctls are implemented in other userspace applications\n  which might not fill it. The added code checks that it\u0027s not zero,\n  to prevent any regressions.",
  "id": "GHSA-fv49-mrx3-2jvj",
  "modified": "2026-07-30T06:32:27Z",
  "published": "2026-01-13T18:31:04Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-68795"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3df375a1e75483b7d973c3cc2e46aa374db8428b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4066b5b546293f44cd6d0e84ece6e3ee7ff27093"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4afcb985355210e1688560dc47e64b94dad35d71"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7b07be1ff1cb6c49869910518650e8d0abc7d25f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7bea09f60f2ad5d232e2db8f1c14e850fd3fd416"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ca9983bc3a1189bd72f9ae449d925a66b2616326"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f9dc0f45d2cd0189ce666288a29d2cc32c2e44d5"
    }
  ],
  "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-FV8W-Q2XX-FC7R

Vulnerability from github – Published: 2026-09-08 18:32 – Updated: 2026-09-08 18:32
VLAI
Details

Heap-based buffer overflow in Windows Universal Disk Format File System Driver (UDFS) allows an authorized attacker to elevate privileges locally.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-69592"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-08T18:19:29Z",
    "severity": "HIGH"
  },
  "details": "Heap-based buffer overflow in Windows Universal Disk Format File System Driver (UDFS) allows an authorized attacker to elevate privileges locally.",
  "id": "GHSA-fv8w-q2xx-fc7r",
  "modified": "2026-09-08T18:32:47Z",
  "published": "2026-09-08T18:32:47Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-69592"
    },
    {
      "type": "WEB",
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69592"
    }
  ],
  "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-FV9Q-MGWX-M5GR

Vulnerability from github – Published: 2023-07-10 21:31 – Updated: 2024-04-04 05:54
VLAI
Details

A heap buffer overflow vulnerability was found in sox, in the lsx_readbuf function at sox/src/formats_i.c:98:16. This flaw can lead to a denial of service, code execution, or information disclosure.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-34432"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122",
      "CWE-787"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-07-10T21:15:10Z",
    "severity": "HIGH"
  },
  "details": "A heap buffer overflow vulnerability was found in sox, in the lsx_readbuf function at sox/src/formats_i.c:98:16. This flaw can lead to a denial of service, code execution, or information disclosure.",
  "id": "GHSA-fv9q-mgwx-m5gr",
  "modified": "2024-04-04T05:54:11Z",
  "published": "2023-07-10T21:31:01Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-34432"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2023-34432"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2212291"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

Mitigation

Pre-design: Use a language or compiler that performs automatic bounds checking.

Mitigation
Architecture and Design

Use an abstraction library to abstract away risky APIs. Not a complete solution.

Mitigation MIT-10
Operation Build and Compilation

Strategy: Environment Hardening

  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.
  • D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
Mitigation MIT-11
Operation Build and Compilation

Strategy: Environment Hardening

  • Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.
  • Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.
  • For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].
Mitigation
Implementation

Implement and perform bounds checking on input.

Mitigation
Implementation

Strategy: Libraries or Frameworks

Do not use dangerous functions such as gets. Look for their safe equivalent, which checks for the boundary.

Mitigation
Operation

Use OS-level preventative functionality. This is not a complete solution, but it provides some defense in depth.

CAPEC-92: Forced Integer Overflow

This attack forces an integer variable to go out of range. The integer variable is often used as an offset such as size of memory allocation or similarly. The attacker would typically control the value of such variable and try to get it out of range. For instance the integer in question is incremented past the maximum possible value, it may wrap to become a very small, or negative number, therefore providing a very incorrect value which can lead to unexpected behavior. At worst the attacker can execute arbitrary code.