CVE-2026-91776.

Disclosure summary

### 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 deserial

Source-specific records & product guidance

Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.

Original records & references

• NIST NVD record
• CVE Program record
• github.com — Reviewed advisory

PUBLISHED 2026-09-30T11:36:55-04:00
MODIFIED 2026-09-30T11:36:57-04:00
INGESTED 2026-10-06T11:43:09-04:00