Vulnerability-Lookup

CVE-2026-83557 (GCVE-0-2026-83557)

Vulnerability from cvelistv5 – Published: 2026-09-01 14:57 – Updated: 2026-09-01 17:46

Title

jackson-databind omits java.lang.Comparable from DefaultBaseTypeLimitingValidator's unsafe base types

Summary

DefaultBaseTypeLimitingValidator is the PolymorphicTypeValidator applied automatically whenever @JsonTypeInfo is used without an explicitly configured custom validator. It denies polymorphic resolution only for a fixed set of "unsafe base types", and its isSafeSubType method returns true unconditionally for every base type outside that set. java.lang.Comparable was absent from the list despite being implemented by a very large fraction of JDK and application classes, comparable in breadth to java.io.Serializable, which is on the list for that reason. An application declaring an @JsonTypeInfo-annotated property or class with Comparable as its base type, and no custom PolymorphicTypeValidator, will accept a type identifier for essentially any class implementing Comparable. This yields an attacker-controlled object instantiation primitive; a demonstrated case constructs a java.io.File for an arbitrary attacker-chosen path, which becomes path-traversal-adjacent if the application subsequently calls path-sensitive methods on the value. No class implementing Comparable has been identified that yields code execution through deserialization alone. Global Default Typing via activateDefaultTyping is not affected, because that method structurally requires an explicit PolymorphicTypeValidator argument. This affects com.fasterxml.jackson.core:jackson-databind from 2.11.0 before 2.18.10, from 2.19.0 before 2.21.6, and from 2.22.0 before 2.22.2, and tools.jackson.core:jackson-databind from 3.0.0 before 3.1.6 and from 3.2.0 before 3.2.2. Users should upgrade to 2.18.10, 2.21.6, 2.22.2, 3.1.6, or 3.2.2.

Severity

5.6 (Medium)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-01 17:46 UTC

CWE

CWE-502 - Deserialization of Untrusted Data
CWE-915 - Improperly Controlled Modification of Dynamically-Determined Object Attributes

Assigner

HeroDevs mitre root

References

4 references

URL	Tags
https://github.com/FasterXML/jackson-databind/sec…	third-party-advisory
https://github.com/FasterXML/jackson-databind/pull/6155	patchissue-tracking
https://github.com/FasterXML/jackson-databind/iss…	issue-tracking
https://github.com/FasterXML/jackson-databind/com…	patch

Impacted products

2 products

Vendor	Product	Version	CPE status
FasterXML	jackson-databind	Affected: 2.11.0 , < 2.18.10 (maven) Affected: 2.19.0 , < 2.21.6 (maven) Affected: 2.22.0 , < 2.22.2 (maven)	guessed
FasterXML	jackson-databind	Affected: 3.0.0 , < 3.1.6 (maven) Affected: 3.2.0 , < 3.2.2 (maven)	guessed

Date Public

2026-09-01 00:00

Credits

prvazsahnazarov Tatu Saloranta (cowtowncoder)

Show details on NVD website

JSON

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Global Default Typing via activateDefaultTyping is not affected, because that method structurally requires an explicit PolymorphicTypeValidator argument. This affects com.fasterxml.jackson.core:jackson-databind from 2.11.0 before 2.18.10, from 2.19.0 before 2.21.6, and from 2.22.0 before 2.22.2, and tools.jackson.core:jackson-databind from 3.0.0 before 3.1.6 and from 3.2.0 before 3.2.2. Users should upgrade to 2.18.10, 2.21.6, 2.22.2, 3.1.6, or 3.2.2.\", \"supportingMedia\": [{\"type\": \"text/html\", \"base64\": false, \"value\": \"\u003cp\u003eDefaultBaseTypeLimitingValidator is the PolymorphicTypeValidator applied automatically whenever @JsonTypeInfo is used without an explicitly configured custom validator. 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Global Default Typing via activateDefaultTyping is not affected, because that method structurally requires an explicit PolymorphicTypeValidator argument. This affects com.fasterxml.jackson.core:jackson-databind from 2.11.0 before 2.18.10, from 2.19.0 before 2.21.6, and from 2.22.0 before 2.22.2, and tools.jackson.core:jackson-databind from 3.0.0 before 3.1.6 and from 3.2.0 before 3.2.2. Users should upgrade to 2.18.10, 2.21.6, 2.22.2, 3.1.6, or 3.2.2.\u003c/p\u003e\"}]}], \"references\": [{\"url\": \"https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-gx83-3vf8-gh7j\", \"name\": \"GHSA-gx83-3vf8-gh7j\", \"tags\": [\"third-party-advisory\"]}, {\"url\": \"https://github.com/FasterXML/jackson-databind/pull/6155\", \"name\": \"FasterXML/jackson-databind#6155\", \"tags\": [\"patch\", \"issue-tracking\"]}, {\"url\": \"https://github.com/FasterXML/jackson-databind/issues/6156\", \"name\": \"FasterXML/jackson-databind#6156\", \"tags\": [\"issue-tracking\"]}, {\"url\": \"https://github.com/FasterXML/jackson-databind/commit/eb3b7fc0f9c0d27f471550ac3316b17d1987388f\", \"name\": \"Fix commit (2.x line, forward-merged to 2.21, 2.22 and the 3.x branches)\", \"tags\": [\"patch\"]}], \"metrics\": [{\"format\": \"CVSS\", \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}], \"cvssV3_1\": {\"version\": \"3.1\", \"attackVector\": \"NETWORK\", \"attackComplexity\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"userInteraction\": \"NONE\", \"scope\": \"UNCHANGED\", \"confidentialityImpact\": \"LOW\", \"integrityImpact\": \"LOW\", \"availabilityImpact\": \"LOW\", \"baseSeverity\": \"MEDIUM\", \"baseScore\": 5.6, \"vectorString\": \"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L\"}}], \"workarounds\": [{\"lang\": \"en\", \"value\": \"Configure an explicit restrictive PolymorphicTypeValidator rather than relying on the default validator, or avoid declaring java.lang.Comparable as the base type of an @JsonTypeInfo-annotated property or class. Narrowing the declared base type to an application-specific interface also removes the exposure.\", \"supportingMedia\": [{\"type\": \"text/html\", \"base64\": false, \"value\": \"\u003cp\u003eConfigure an explicit restrictive PolymorphicTypeValidator rather than relying on the default validator, or avoid declaring java.lang.Comparable as the base type of an @JsonTypeInfo-annotated property or class. Narrowing the declared base type to an application-specific interface also removes the exposure.\u003c/p\u003e\"}]}], \"solutions\": [{\"lang\": \"en\", \"value\": \"Upgrade to jackson-databind 2.18.10, 2.21.6, 2.22.2 (com.fasterxml.jackson.core) or 3.1.6, 3.2.2 (tools.jackson.core). The fix adds java.lang.Comparable to the UnsafeBaseTypes denylist in DefaultBaseTypeLimitingValidator, so polymorphic resolution against a Comparable base type is denied outright. Applications that legitimately need polymorphic handling of a Comparable-typed property must configure an explicit PolymorphicTypeValidator, for example a BasicPolymorphicTypeValidator with an allow-list of permitted subtypes.\", \"supportingMedia\": [{\"type\": \"text/html\", \"base64\": false, \"value\": \"\u003cp\u003eUpgrade to jackson-databind 2.18.10, 2.21.6, 2.22.2 (com.fasterxml.jackson.core) or 3.1.6, 3.2.2 (tools.jackson.core). The fix adds java.lang.Comparable to the UnsafeBaseTypes denylist in DefaultBaseTypeLimitingValidator, so polymorphic resolution against a Comparable base type is denied outright. Applications that legitimately need polymorphic handling of a Comparable-typed property must configure an explicit PolymorphicTypeValidator, for example a BasicPolymorphicTypeValidator with an allow-list of permitted subtypes.\u003c/p\u003e\"}]}], \"timeline\": [{\"time\": \"2026-08-11T02:58:00.000Z\", \"lang\": \"en\", \"value\": \"Fix committed upstream (FasterXML/jackson-databind#6155)\"}, {\"time\": \"2026-09-01T00:00:00.000Z\", \"lang\": \"en\", \"value\": \"GitHub Security Advisory GHSA-gx83-3vf8-gh7j published by the maintainer\"}], \"credits\": [{\"lang\": \"en\", \"value\": \"prvazsahnazarov\", \"type\": \"reporter\"}, {\"lang\": \"en\", \"value\": \"Tatu Saloranta (cowtowncoder)\", \"type\": \"remediation developer\"}], \"source\": {\"discovery\": \"EXTERNAL\"}}, \"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-83557\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-09-01T17:46:23.527612Z\"}}}], \"references\": [{\"url\": \"https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-gx83-3vf8-gh7j\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-09-01T17:46:36.225Z\"}}]}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-83557\", \"assignerOrgId\": \"36c7be3b-2937-45df-85ea-ca7133ea542c\", \"state\": \"PUBLISHED\", \"assignerShortName\": \"HeroDevs\", \"dateReserved\": \"2026-08-31T18:32:14.405Z\", \"datePublished\": \"2026-09-01T14:57:01.340Z\", \"dateUpdated\": \"2026-09-01T17:46:40.145Z\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-83557

Vulnerability from fkie_nvd - Published: 2026-09-01 15:17 - Updated: 2026-09-01 18:17

Severity

5.6 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Summary

References

	URL	Tags
	36c7be3b-2937-45df-85ea-ca7133ea542c	https://github.com/FasterXML/jackson-databind/commit/eb3b7fc0f9c0d27f471550ac3316b17d1987388f
	36c7be3b-2937-45df-85ea-ca7133ea542c	https://github.com/FasterXML/jackson-databind/issues/6156
	36c7be3b-2937-45df-85ea-ca7133ea542c	https://github.com/FasterXML/jackson-databind/pull/6155
	36c7be3b-2937-45df-85ea-ca7133ea542c	https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-gx83-3vf8-gh7j
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-gx83-3vf8-gh7j

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.maven.apache.org/maven2",
          "defaultStatus": "unaffected",
          "packageName": "com.fasterxml.jackson.core:jackson-databind",
          "product": "jackson-databind",
          "programFiles": [
            "src/main/java/com/fasterxml/jackson/databind/jsontype/DefaultBaseTypeLimitingValidator.java"
          ],
          "programRoutines": [
            {
              "name": "com.fasterxml.jackson.databind.jsontype.DefaultBaseTypeLimitingValidator.isUnsafeBaseType"
            }
          ],
          "repo": "https://github.com/FasterXML/jackson-databind",
          "vendor": "FasterXML",
          "versions": [
            {
              "lessThan": "2.18.10",
              "status": "affected",
              "version": "2.11.0",
              "versionType": "maven"
            },
            {
              "lessThan": "2.21.6",
              "status": "affected",
              "version": "2.19.0",
              "versionType": "maven"
            },
            {
              "lessThan": "2.22.2",
              "status": "affected",
              "version": "2.22.0",
              "versionType": "maven"
            }
          ]
        },
        {
          "collectionURL": "https://repo.maven.apache.org/maven2",
          "defaultStatus": "unaffected",
          "packageName": "tools.jackson.core:jackson-databind",
          "product": "jackson-databind",
          "programFiles": [
            "src/main/java/tools/jackson/databind/jsontype/DefaultBaseTypeLimitingValidator.java"
          ],
          "programRoutines": [
            {
              "name": "tools.jackson.databind.jsontype.DefaultBaseTypeLimitingValidator.isUnsafeBaseType"
            }
          ],
          "repo": "https://github.com/FasterXML/jackson-databind",
          "vendor": "FasterXML",
          "versions": [
            {
              "lessThan": "3.1.6",
              "status": "affected",
              "version": "3.0.0",
              "versionType": "maven"
            },
            {
              "lessThan": "3.2.2",
              "status": "affected",
              "version": "3.2.0",
              "versionType": "maven"
            }
          ]
        }
      ],
      "source": "36c7be3b-2937-45df-85ea-ca7133ea542c"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "DefaultBaseTypeLimitingValidator is the PolymorphicTypeValidator applied automatically whenever @JsonTypeInfo is used without an explicitly configured custom validator. It denies polymorphic resolution only for a fixed set of \"unsafe base types\", and its isSafeSubType method returns true unconditionally for every base type outside that set. java.lang.Comparable was absent from the list despite being implemented by a very large fraction of JDK and application classes, comparable in breadth to java.io.Serializable, which is on the list for that reason. An application declaring an @JsonTypeInfo-annotated property or class with Comparable as its base type, and no custom PolymorphicTypeValidator, will accept a type identifier for essentially any class implementing Comparable. This yields an attacker-controlled object instantiation primitive; a demonstrated case constructs a java.io.File for an arbitrary attacker-chosen path, which becomes path-traversal-adjacent if the application subsequently calls path-sensitive methods on the value. No class implementing Comparable has been identified that yields code execution through deserialization alone. Global Default Typing via activateDefaultTyping is not affected, because that method structurally requires an explicit PolymorphicTypeValidator argument. This affects com.fasterxml.jackson.core:jackson-databind from 2.11.0 before 2.18.10, from 2.19.0 before 2.21.6, and from 2.22.0 before 2.22.2, and tools.jackson.core:jackson-databind from 3.0.0 before 3.1.6 and from 3.2.0 before 3.2.2. Users should upgrade to 2.18.10, 2.21.6, 2.22.2, 3.1.6, or 3.2.2."
    }
  ],
  "id": "CVE-2026-83557",
  "lastModified": "2026-09-01T18:17:47.387",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 5.6,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 3.4,
        "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-83557",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-01T17:46:23.527612Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-01T15:17:37.987",
  "references": [
    {
      "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
      "url": "https://github.com/FasterXML/jackson-databind/commit/eb3b7fc0f9c0d27f471550ac3316b17d1987388f"
    },
    {
      "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
      "url": "https://github.com/FasterXML/jackson-databind/issues/6156"
    },
    {
      "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
      "url": "https://github.com/FasterXML/jackson-databind/pull/6155"
    },
    {
      "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
      "url": "https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-gx83-3vf8-gh7j"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-gx83-3vf8-gh7j"
    }
  ],
  "sourceIdentifier": "36c7be3b-2937-45df-85ea-ca7133ea542c",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-502"
        },
        {
          "lang": "en",
          "value": "CWE-915"
        }
      ],
      "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
      "type": "Secondary"
    }
  ]
}

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

CVE-2026-83557 (GCVE-0-2026-83557)

FKIE_CVE-2026-83557

Tags

Sightings

Nomenclature