Vulnerability-Lookup

GHSA-568F-PV23-39P4

Vulnerability from github – Published: 2026-09-08 16:37 – Updated: 2026-09-08 16:37

Summary

NLTK: Stable FrameNet and NKJP readers parse outside-root XML

Details

Summary

Published nltk==3.9.4 still contains several XML-reader entrypoints that build parser paths from caller-controlled selectors or trusted-looking index state without preserving the corpus-root boundary.

Details

Vulnerability type: Path traversal and trusted-root bypass
Affected component: FramenetCorpusReader.frame_by_name, FramenetCorpusReader.doc, FramenetCorpusReader.lu, NKJPCorpusReader.header
Affected versions: Published 3.9.4 reproduced. Current source v3.10.0-rc2 acted as a negative control and blocked the same payloads.
Patched versions: Patched in version 3.10.0, which includes the path-safety rejections seen in the release candidate.
Root cause: Stable reader paths still construct raw XML filenames from unsafe selectors, poisoned index state, or unsafe file identifiers.

I confirmed four public stable entrypoints return parsed outside-root content: a parent-segment traversal frame name, a poisoned fulltext index filename, a poisoned LU id, and an unsafe NKJP header file identifier. Current source rejects the same payloads with explicit path-safety errors, which shows the bug is real but version-scoped to the published stable package.

PoC

Preconditions - The application exposes FrameNet or NKJP reader APIs while trusting NLTK to keep XML parsing inside a corpus root.

Steps 1. Create a minimal FrameNet or NKJP corpus root and place attacker-chosen XML files outside that root. 2. Feed unsafe selectors or poisoned index state into the relevant public stable 3.9.4 APIs. 3. Observe frame_by_name, doc, lu(...).exemplars, or header return parsed outside-root values. 4. Run the same payloads against current source and observe explicit path-safety rejections.

Minimal reproducible excerpt

framenet_frame_definition FRAME_LEAK
framenet_doc_text DOC_LEAK
framenet_lu_text LU_LEAK
nkjp_header_title HEADER_LEAK

Impact

Applications that process attacker-influenced FrameNet or NKJP corpus selectors or state can be made to parse XML outside the trusted corpus root through normal public reader responses.

Remediation

Keep these reader paths on the same root-confinement model as CorpusReader.open() and nltk.pathsec. Reject unsafe path components before constructing filenames from frame names, document filenames, LU ids, or NKJP file identifiers.

Resources

https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/framenet.py#L1366-L1369
https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/framenet.py#L1456-L1460
https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/framenet.py#L1803-L1810
https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/nkjp.py#L96-L103
https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/nkjp.py#L251-L256
https://github.com/nltk/nltk/blob/v3.10.0-rc2/nltk/corpus/reader/framenet.py#L1388-L1399
https://github.com/nltk/nltk/blob/v3.10.0-rc2/nltk/corpus/reader/nkjp.py#L96-L128

Severity

5.9 (Medium)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

8.2 (High)


                  
                    CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.9.4"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "nltk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.10.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-62385"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22",
      "CWE-706",
      "CWE-73"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-08T16:37:18Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\nPublished `nltk==3.9.4` still contains several XML-reader entrypoints that build parser paths from caller-controlled selectors or trusted-looking index state without preserving the corpus-root boundary.\n\n### Details\n\n- **Vulnerability type:** Path traversal and trusted-root bypass\n- **Affected component:** `FramenetCorpusReader.frame_by_name`, `FramenetCorpusReader.doc`, `FramenetCorpusReader.lu`, `NKJPCorpusReader.header`\n- **Affected versions:** Published `3.9.4` reproduced. Current source `v3.10.0-rc2` acted as a negative control and blocked the same payloads.\n- **Patched versions:** Patched in version 3.10.0, which includes the path-safety rejections seen in the release candidate.\n- **Root cause:** Stable reader paths still construct raw XML filenames from unsafe selectors, poisoned index state, or unsafe file identifiers.\n\nI confirmed four public stable entrypoints return parsed outside-root content: a parent-segment traversal frame name, a poisoned fulltext index filename, a poisoned LU id, and an unsafe NKJP header file identifier. Current source rejects the same payloads with explicit path-safety errors, which shows the bug is real but version-scoped to the published stable package.\n\n### PoC\n\n**Preconditions**\n- The application exposes FrameNet or NKJP reader APIs while trusting NLTK to keep XML parsing inside a corpus root.\n\n**Steps**\n1. Create a minimal FrameNet or NKJP corpus root and place attacker-chosen XML files outside that root.\n2. Feed unsafe selectors or poisoned index state into the relevant public stable `3.9.4` APIs.\n3. Observe `frame_by_name`, `doc`, `lu(...).exemplars`, or `header` return parsed outside-root values.\n4. Run the same payloads against current source and observe explicit path-safety rejections.\n\n**Minimal reproducible excerpt**\n\n```text\nframenet_frame_definition FRAME_LEAK\nframenet_doc_text DOC_LEAK\nframenet_lu_text LU_LEAK\nnkjp_header_title HEADER_LEAK\n```\n\n### Impact\n\nApplications that process attacker-influenced FrameNet or NKJP corpus selectors or state can be made to parse XML outside the trusted corpus root through normal public reader responses.\n\n### Remediation\n\nKeep these reader paths on the same root-confinement model as `CorpusReader.open()` and `nltk.pathsec`. Reject unsafe path components before constructing filenames from frame names, document filenames, LU ids, or NKJP file identifiers.\n\n### Resources\n\n- https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/framenet.py#L1366-L1369\n- https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/framenet.py#L1456-L1460\n- https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/framenet.py#L1803-L1810\n- https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/nkjp.py#L96-L103\n- https://github.com/nltk/nltk/blob/3.9.4/nltk/corpus/reader/nkjp.py#L251-L256\n- https://github.com/nltk/nltk/blob/v3.10.0-rc2/nltk/corpus/reader/framenet.py#L1388-L1399\n- https://github.com/nltk/nltk/blob/v3.10.0-rc2/nltk/corpus/reader/nkjp.py#L96-L128",
  "id": "GHSA-568f-pv23-39p4",
  "modified": "2026-09-08T16:37:18Z",
  "published": "2026-09-08T16:37:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/security/advisories/GHSA-568f-pv23-39p4"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-62385"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/pull/3579"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/pull/3581"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/commit/7d1389d0789c1eca56bd0ed444089e0a3972e3ed"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/commit/bf3bf32786791394a1008258b4917a7f2d4dbcda"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nltk/nltk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/releases/tag/v3.10.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3728.yaml"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/nltk-path-traversal-via-framenet-and-nkjp-readers"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "NLTK: Stable FrameNet and NKJP readers parse outside-root XML"
}

CVE-2026-62385 (GCVE-0-2026-62385)

Vulnerability from cvelistv5 – Published: 2026-08-22 14:12 – Updated: 2026-08-24 19:07

Title

NLTK 3.9.4 Path Traversal via FrameNet and NKJP Readers

Summary

NLTK versions before 3.10.0 contain a path traversal vulnerability in FramenetCorpusReader and NKJPCorpusReader that allows attackers to parse XML files outside the corpus root by supplying unsafe selectors or poisoned index state. Attackers can exploit frame_by_name, doc, lu, and header methods with crafted parameters to read arbitrary XML files accessible to the application.

Severity

8.2 (High)


                        
                          CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

5.9 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-24 19:07 UTC

CWE

CWE-73 - External Control of File Name or Path

Assigner

VulnCheck mitre root

References

2 references

URL	Tags
https://github.com/nltk/nltk/security/advisories/…	vendor-advisory
https://www.vulncheck.com/advisories/nltk-path-tr…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
nltk	nltk	Affected: 0 , < 3.10.0 (semver) Unaffected: 3.10.0 (semver) cpe:2.3:a:nltk:nltk::::::::

Date Public

2026-08-07 00:00

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-62385",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-24T19:07:48.518788Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-24T19:07:55.247Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
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            ],
            "url": "https://github.com/nltk/nltk/security/advisories/GHSA-568f-pv23-39p4"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
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        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
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            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
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            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
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          "cvssV3_1": {
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          "url": "https://github.com/nltk/nltk/security/advisories/GHSA-568f-pv23-39p4"
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    "datePublished": "2026-08-22T14:12:37.962Z",
    "dateReserved": "2026-07-13T22:40:54.412Z",
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    "state": "PUBLISHED"
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}

PYSEC-2026-3728

Vulnerability from pysec - Published: 2026-08-22 15:16 - Updated: 2026-09-01 08:54

Details

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Impacted products

Name	purl
nltk	pkg:pypi/nltk

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {},
      "package": {
        "ecosystem": "PyPI",
        "name": "nltk",
        "purl": "pkg:pypi/nltk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.10.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.8",
        "0.9",
        "0.9.3",
        "0.9.4",
        "0.9.5",
        "0.9.6",
        "0.9.7",
        "0.9.8",
        "0.9.9",
        "2.0.1",
        "2.0.1rc1",
        "2.0.1rc2-git",
        "2.0.1rc3",
        "2.0.1rc4",
        "2.0.2",
        "2.0.3",
        "2.0.4",
        "2.0.5",
        "2.0b4",
        "2.0b5",
        "2.0b6",
        "2.0b7",
        "2.0b8",
        "2.0b9",
        "3.0.0",
        "3.0.0b1",
        "3.0.0b2",
        "3.0.1",
        "3.0.2",
        "3.0.3",
        "3.0.4",
        "3.0.5",
        "3.1",
        "3.2",
        "3.2.1",
        "3.2.2",
        "3.2.3",
        "3.2.4",
        "3.2.5",
        "3.3",
        "3.4",
        "3.4.1",
        "3.4.2",
        "3.4.3",
        "3.4.4",
        "3.4.5",
        "3.5",
        "3.5b1",
        "3.6",
        "3.6.1",
        "3.6.2",
        "3.6.3",
        "3.6.4",
        "3.6.5",
        "3.6.6",
        "3.6.7",
        "3.7",
        "3.8",
        "3.8.1",
        "3.9",
        "3.9.1",
        "3.9.2",
        "3.9.3",
        "3.9.4",
        "3.9b1"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-62385",
    "GHSA-568f-pv23-39p4"
  ],
  "details": "NLTK versions before 3.10.0 contain a path traversal vulnerability in FramenetCorpusReader and NKJPCorpusReader that allows attackers to parse XML files outside the corpus root by supplying unsafe selectors or poisoned index state. Attackers can exploit frame_by_name, doc, lu, and header methods with crafted parameters to read arbitrary XML files accessible to the application.",
  "id": "PYSEC-2026-3728",
  "modified": "2026-09-01T08:54:51.495356Z",
  "published": "2026-08-22T15:16:18.833Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/nltk-path-traversal-via-framenet-and-nkjp-readers"
    },
    {
      "type": "EVIDENCE",
      "url": "https://github.com/nltk/nltk/security/advisories/GHSA-568f-pv23-39p4"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-568F-PV23-39P4

Summary

Details

PoC

Impact

Remediation

Resources

CVE-2026-62385 (GCVE-0-2026-62385)

PYSEC-2026-3728

Tags

Sightings

Nomenclature