GHSA-RMJ7-2VXQ-3G9F

Vulnerability from github – Published: 2026-06-23 21:22 – Updated: 2026-06-23 21:22
VLAI
Summary
jackson-databind has an array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)
Details

Summary

BasicPolymorphicTypeValidator.Builder.allowIfSubTypeIsArray() allowlists any array type based only on clazz.isArray(), without validating the array's component (element) type against the configured allowlist. A PTV built with allowIfSubTypeIsArray() plus an explicit concrete-type allowlist therefore still permits EvilType[] even though EvilType is not allowlisted. When Jackson deserializes the elements and no per-element type IDs are present, it instantiates the component type directly with no further PTV check, bypassing the allowlist.

Impact

Applications using BasicPolymorphicTypeValidator with allowIfSubTypeIsArray() as a safeguard get no protection for concrete array component types; an attacker controlling JSON can instantiate non-allowlisted types via an array wrapper, re-opening the gadget-instantiation risk PTV is meant to prevent.

Affected / Patched (verified via git tag --contains)

  • 2.18 line: >= 2.10.0, < 2.18.8 -> fixed in 2.18.8
  • 2.19-2.21 line: >= 2.19.0, < 2.21.4 -> fixed in 2.21.4
  • 3.x line: >= 3.0.0, < 3.1.4 -> fixed in 3.1.4

PolymorphicTypeValidator was added in 2.10.0 so vulnerability N/A for versions prior to that.

Severity / CWE

Maintainer: significant. Reporter: HIGH. CWE-184 (Incomplete List of Disallowed Inputs); related CWE-502.

Upstream fix

FasterXML/jackson-databind#5981; fix PR #5983 (24529da), 2.18 backport PR #5984 (01d1692). Released 2026-06-04 in 2.18.8 / 2.21.4 / 3.1.4.

Credits

Omkhar Arasaratnam (@omkhar) - finder.

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

{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.10.0"
            },
            {
              "fixed": "2.18.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.19.0"
            },
            {
              "fixed": "2.21.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Maven",
        "name": "tools.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54513"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-184"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-23T21:22:15Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Summary\n`BasicPolymorphicTypeValidator.Builder.allowIfSubTypeIsArray()` allowlists any array type based only on `clazz.isArray()`, without validating the array\u0027s component (element) type against the configured allowlist. A PTV built with `allowIfSubTypeIsArray()` plus an explicit concrete-type allowlist therefore still permits `EvilType[]` even though `EvilType` is not allowlisted. When Jackson deserializes the elements and no per-element type IDs are present, it instantiates the component type directly with no further PTV check, bypassing the allowlist.\n\n## Impact\nApplications using `BasicPolymorphicTypeValidator` with `allowIfSubTypeIsArray()` as a safeguard get no protection for concrete array component types; an attacker controlling JSON can instantiate non-allowlisted types via an array wrapper, re-opening the gadget-instantiation risk PTV is meant to prevent.\n\n## Affected / Patched (verified via `git tag --contains`)\n- 2.18 line: `\u003e= 2.10.0, \u003c 2.18.8` -\u003e fixed in **2.18.8**\n- 2.19-2.21 line: `\u003e= 2.19.0, \u003c 2.21.4` -\u003e fixed in **2.21.4**\n- 3.x line: `\u003e= 3.0.0, \u003c 3.1.4` -\u003e fixed in **3.1.4**\n\n`PolymorphicTypeValidator` was added in 2.10.0 so vulnerability N/A for versions prior to that.\n\n## Severity / CWE\nMaintainer: significant. Reporter: HIGH. CWE-184 (Incomplete List of Disallowed Inputs); related CWE-502.\n\n## Upstream fix\nFasterXML/jackson-databind#5981; fix PR #5983 (`24529da`), 2.18 backport PR #5984 (`01d1692`). Released 2026-06-04 in 2.18.8 / 2.21.4 / 3.1.4.\n\n## Credits\nOmkhar Arasaratnam (@omkhar) - finder.",
  "id": "GHSA-rmj7-2vxq-3g9f",
  "modified": "2026-06-23T21:22:15Z",
  "published": "2026-06-23T21:22:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-rmj7-2vxq-3g9f"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/issues/5981"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/issues/5983"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/pull/5984"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/commit/01d1692c8d0ed03e51a0e3c4f8a9e6908e4931e5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/commit/24529da29fdf46ff94ca38de9ebf31cd188f5e8e"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/FasterXML/jackson-databind"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "jackson-databind has an array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)"
}


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