Vulnerability-Lookup

GHSA-WV8Q-QHHJ-9H54

Vulnerability from github – Published: 2026-09-30 15:36 – Updated: 2026-09-30 15:36

Summary

jackson-databind retains every unknown raw type ID

Details

Summary

With @JsonTypeInfo(use = Id.NAME, defaultImpl = ...), every distinct unknown raw type ID selects the same fallback deserializer but is retained as a separate key in TypeDeserializerBase._deserializers. An attacker who can repeatedly supply new unknown type IDs can grow this process-lifetime cache without a configured bound.

Details

The affected path is TypeDeserializerBase._findDeserializer(). After an unknown name-based type ID resolves to the configured fallback/default implementation, jackson-databind caches the result under the attacker-provided raw typeId. Although all such IDs select the same fallback deserializer, each new string remains a distinct cache key.

The behavior is runtime-confirmed in jackson-databind 2.22.1 and 3.2.1. Current 2.22 and 3.2 source branches retained the unbounded _deserializers map and per-raw-ID cache write when rechecked. The earlier affected floor has not been established, patched versions are: 2.18.11, 2.21.7, 2.22.3, 3.1.7 and 3.2.3.

The vulnerable application must enable name-based polymorphism with a defaultImpl or equivalent fallback, accept attacker-influenced type IDs, and reuse a long-lived mapper/type deserializer across requests.

Suggested correction: avoid caching each unknown raw ID when every such ID resolves to the same fallback, use a fallback sentinel, or use an explicitly bounded concurrency-safe cache. A regression should contrast many distinct unknown IDs with repetitions of one unknown ID across requests.

PoC

Configure a polymorphic base type with @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, defaultImpl = Fallback.class) and deserialize inputs containing unknown type names through the same mapper. Inspect TypeDeserializerBase._deserializers after the run.

On affected 2.x and 3.x versions, 10,000 distinct unknown raw type IDs produce 10,000 retained cache entries even though every input selects the same fallback deserializer. A matched control that repeats one unknown ID 10,000 times produces one retained entry. This isolates attacker-controlled key cardinality from ordinary request count.

Impact

Where the stated polymorphic fallback configuration is exposed to attacker-influenced type IDs, distinct inputs cause incremental process-lifetime memory retention and eventual availability pressure or denial of service. This is not claimed as a single-request allocation spike, and no fixed bytes-per-ID or time-to-out-of-memory value is asserted. No confidentiality, integrity, or code-execution impact is claimed.

Requested credit: Daniel Birtwhistle

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

JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.18.10"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.0"
            },
            {
              "fixed": "2.18.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.21.6"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.19.0"
            },
            {
              "fixed": "2.21.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.22.2"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.22.0"
            },
            {
              "fixed": "2.22.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.1.6"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "tools.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.1.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.2.2"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "tools.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.2.0"
            },
            {
              "fixed": "3.2.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-91776"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-30T15:36:55Z",
    "nvd_published_at": "2026-09-23T03:17:04Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nWith `@JsonTypeInfo(use = Id.NAME, defaultImpl = ...)`, every distinct unknown\nraw type ID selects the same fallback deserializer but is retained as a\nseparate key in `TypeDeserializerBase._deserializers`. An attacker who can\nrepeatedly supply new unknown type IDs can grow this process-lifetime cache\nwithout a configured bound.\n\n### Details\n\nThe affected path is `TypeDeserializerBase._findDeserializer()`. After an\nunknown name-based type ID resolves to the configured fallback/default\nimplementation, jackson-databind caches the result under the attacker-provided\nraw `typeId`. Although all such IDs select the same fallback deserializer, each\nnew string remains a distinct cache key.\n\nThe behavior is runtime-confirmed in jackson-databind 2.22.1 and 3.2.1.\nCurrent 2.22 and 3.2 source branches retained the unbounded `_deserializers`\nmap and per-raw-ID cache write when rechecked. The earlier affected floor has\nnot been established, patched versions are: 2.18.11, 2.21.7, 2.22.3, 3.1.7 and 3.2.3.\n\nThe vulnerable application must enable name-based polymorphism with a\n`defaultImpl` or equivalent fallback, accept attacker-influenced type IDs, and\nreuse a long-lived mapper/type deserializer across requests.\n\nSuggested correction: avoid caching each unknown raw ID when every such ID\nresolves to the same fallback, use a fallback sentinel, or use an explicitly\nbounded concurrency-safe cache. A regression should contrast many distinct\nunknown IDs with repetitions of one unknown ID across requests.\n\n### PoC\n\nConfigure a polymorphic base type with\n`@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, defaultImpl = Fallback.class)` and\ndeserialize inputs containing unknown type names through the same mapper.\nInspect `TypeDeserializerBase._deserializers` after the run.\n\nOn affected 2.x and 3.x versions, 10,000 distinct unknown raw type IDs produce\n10,000 retained cache entries even though every input selects the same\nfallback deserializer. A matched control that repeats one unknown ID 10,000\ntimes produces one retained entry. This isolates attacker-controlled key\ncardinality from ordinary request count.\n\n### Impact\n\nWhere the stated polymorphic fallback configuration is exposed to\nattacker-influenced type IDs, distinct inputs cause incremental\nprocess-lifetime memory retention and eventual availability pressure or\ndenial of service. This is not claimed as a single-request allocation spike,\nand no fixed bytes-per-ID or time-to-out-of-memory value is asserted. No\nconfidentiality, integrity, or code-execution impact is claimed.\n\nRequested credit: Daniel Birtwhistle",
  "id": "GHSA-wv8q-qhhj-9h54",
  "modified": "2026-09-30T15:36:55Z",
  "published": "2026-09-30T15:36:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-wv8q-qhhj-9h54"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91776"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/issues/6203"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/commit/2870d1d6dc1b7e1c07ee11dd5b04ab71cddbb577"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/FasterXML/jackson-databind"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-2.18.11"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-2.21.7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-2.22.3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-3.1.7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-3.2.3"
    }
  ],
  "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": "jackson-databind retains every unknown raw type ID "
}

CVE-2026-91776 (GCVE-0-2026-91776)

Vulnerability from cvelistv5 – Published: 2026-09-23 02:17 – Updated: 2026-09-23 14:03

Title

jackson-databind: unbounded growth of the type id cache in TypeDeserializerBase retains every unknown raw type ID

Summary

TypeDeserializerBase._findDeserializer() in FasterXML jackson-databind caches the resolved deserializer under the raw, attacker-supplied type ID. When name-based polymorphism is configured with a fallback, for example @JsonTypeInfo(use = Id.NAME, defaultImpl = ...), every distinct unrecognized type ID resolves to the same fallback deserializer but is retained as its own key in the _deserializers map. That map has no configurable bound and lives for the lifetime of the type deserializer, so an attacker who can repeatedly supply fresh unknown type IDs causes monotonic memory retention across requests. The reporter observed 10,000 retained entries from 10,000 distinct unknown IDs, against a single entry for a control that repeated one unknown ID the same number of times, isolating attacker-controlled key cardinality from request volume. Exploitation requires an application that enables name-based polymorphism with a defaultImpl or equivalent fallback, accepts attacker-influenced type IDs, and reuses a long-lived ObjectMapper across requests. The fix stops caching fallback resolutions for unrecognized IDs and bounds both the number of cached entries and the length of a cacheable type ID.

Severity

7.5 (High)


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

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-23 14:02 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

HeroDevs mitre root Scorecard

References

2 references

URL	Tags
https://github.com/FasterXML/jackson-databind/sec…	vendor-advisory
https://github.com/FasterXML/jackson-databind/iss…	patch

Impacted products

2 products

Vendor	Product	Version
FasterXML	jackson-databind	Affected: 2.0.0 , ≤ 2.18.10 (maven) Affected: 2.19.0 , ≤ 2.21.6 (maven) Affected: 2.22.0 , ≤ 2.22.2 (maven)
FasterXML	jackson-databind	Affected: 3.0.0 , ≤ 3.1.6 (maven) Affected: 3.2.0 , ≤ 3.2.2 (maven)

Credits

Daniel Birtwhistle (dabirt)

Show details on NVD website

JSON

To clipboard

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                    "Automatable": "yes"
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                    "Technical Impact": "partial"
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                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-23T14:02:42.582789Z",
                "version": "2.0.3"
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      }
    ],
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            }
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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.

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

GHSA-WV8Q-QHHJ-9H54

Summary

Details

PoC

Impact

CVE-2026-91776 (GCVE-0-2026-91776)

Tags

Sightings

Nomenclature

Related by attack behaviour