PYSEC-2026-1245

Vulnerability from pysec - Published: 2026-07-07 14:34 - Updated: 2026-07-07 17:23
VLAI
Details

Impact

The default cache strategy uses the basename of a remote schema as the name of the file in the cache, e.g. https://example.org/schema.json will be stored as schema.json. This naming allows for conflicts. If an attacker can get a user to run check-jsonschema against a malicious schema URL, e.g., https://example.evil.org/schema.json, they can insert their own schema into the cache and it will be picked up and used instead of the appropriate schema.

Such a cache confusion attack could be used to allow data to pass validation which should have been rejected.

Patches

A patch is in progress but has not yet been released.

Workarounds

  • Users can use --no-cache to disable caching.
  • Users can use --cache-filename to select filenames for use in the cache, or to ensure that other usages do not overwrite the cached schema. (Note: this flag is being deprecated as part of the remediation effort.)
  • Users can explicitly download the schema before use as a local file, as in curl -LOs https://example.org/schema.json; check-jsonschema --schemafile ./schema.json
Impacted products
Name purl
check-jsonschema pkg:pypi/check-jsonschema

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "check-jsonschema",
        "purl": "pkg:pypi/check-jsonschema"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.30.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.1.0",
        "0.1.1",
        "0.10.0",
        "0.10.1",
        "0.10.2",
        "0.11.0",
        "0.12.0",
        "0.13.0",
        "0.14.0",
        "0.14.1",
        "0.14.2",
        "0.14.3",
        "0.15.0",
        "0.15.1",
        "0.16.0",
        "0.16.1",
        "0.16.2",
        "0.17.0",
        "0.17.1",
        "0.18.0",
        "0.18.1",
        "0.18.2",
        "0.18.3",
        "0.18.4",
        "0.19.0",
        "0.19.1",
        "0.19.2",
        "0.2.0",
        "0.2.1",
        "0.20.0",
        "0.21.0",
        "0.22.0",
        "0.23.0",
        "0.23.1",
        "0.23.2",
        "0.23.3",
        "0.24.0",
        "0.24.1",
        "0.25.0",
        "0.26.0",
        "0.26.1",
        "0.26.2",
        "0.26.3",
        "0.27.0",
        "0.27.1",
        "0.27.2",
        "0.27.3",
        "0.27.4",
        "0.28.0",
        "0.28.1",
        "0.28.2",
        "0.28.3",
        "0.28.4",
        "0.28.5",
        "0.28.6",
        "0.29.0",
        "0.29.1",
        "0.29.2",
        "0.29.3",
        "0.29.4",
        "0.3.0",
        "0.3.1",
        "0.3.2",
        "0.4.0",
        "0.4.1",
        "0.5.0",
        "0.5.1",
        "0.6.0",
        "0.7.0",
        "0.7.1",
        "0.8.0",
        "0.8.1",
        "0.8.2",
        "0.9.0",
        "0.9.1"
      ]
    }
  ],
  "aliases": [
    "CVE-2024-53848",
    "GHSA-q6mv-284r-mp36"
  ],
  "details": "### Impact\n\nThe default cache strategy uses the basename of a remote schema as the name of the file in the cache, e.g. `https://example.org/schema.json` will be stored as `schema.json`. This naming allows for conflicts. If an attacker can get a user to run `check-jsonschema` against a malicious schema URL, e.g., `https://example.evil.org/schema.json`, they can insert their own schema into the cache and it will be picked up and used instead of the appropriate schema.\n\nSuch a cache confusion attack could be used to allow data to pass validation which should have been rejected.\n\n### Patches\n\nA patch is in progress but has not yet been released.\n\n### Workarounds\n\n- Users can use `--no-cache` to disable caching.\n- Users can use `--cache-filename` to select filenames for use in the cache, or to ensure that other usages do not overwrite the cached schema. (Note: this flag is being deprecated as part of the remediation effort.)\n- Users can explicitly download the schema before use as a local file, as in `curl -LOs https://example.org/schema.json; check-jsonschema --schemafile ./schema.json`",
  "id": "PYSEC-2026-1245",
  "modified": "2026-07-07T17:23:54.178743Z",
  "published": "2026-07-07T14:34:45.946805Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/python-jsonschema/check-jsonschema/security/advisories/GHSA-q6mv-284r-mp36"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-53848"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python-jsonschema/check-jsonschema/commit/c52714b85e6725b1b24516fbdedacb333b939152"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/python-jsonschema/check-jsonschema"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/check-jsonschema"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-q6mv-284r-mp36"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "check-jsonschema default caching for remote schemas allows for cache confusion"
}



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