cyfenced.com →

[ CVE-2026-91776 · Published 23 Sep 2026 ]

jackson-databind retains every unknown raw type ID

CVSS 7.5 EPSS <1%4 agency advisoriesFix available

[ Why it matters ]Priority signals

  • Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

[ Advisories ]Government CERT advisories

  • NCSC-NLNCSC-2026-0448

    Vulnerabilities fixed in Oracle Fusion Middleware Translated from Dutch

    Probability/damage H/HCVE-2026-54513CVE-2026-56741CVE-2026-59649+191 more CVEs
  • BSI CERT-BundWID-SEC-2026-4078

    Oracle Fusion Middleware: Multiple vulnerabilities Translated from German

    CVE-2026-91212CVE-2023-43622CVE-2026-42779+191 more CVEs
  • CERT-FRCERTFR-2026-AVI-1336

    Multiple vulnerabilities in IBM products Translated from French

    Multiple vulnerabilities have been discovered in IBM products. Some of them allow an attacker to cause remote arbitrary code execution, privilege escalation and remote denial of service.

    CVE-2026-14671CVE-2026-11548CVE-2022-22950+490 more CVEs
  • CERT-FRCERTFR-2026-AVI-1249

    Multiple vulnerabilities in VMware products Translated from French

    Multiple vulnerabilities have been discovered in VMware products. They allow an attacker to cause a security problem not specified by the vendor.

    CVE-2026-75595CVE-2026-53910CVE-2026-56404+288 more CVEs

[ Packages ]Affected open-source packages

  • com.fasterxml.jackson.core:jackson-databind mavenAffected >= 2.0.0, <= 2.18.10 · fixed in 2.18.11 · GHSA-wv8q-qhhj-9h54
  • com.fasterxml.jackson.core:jackson-databind mavenAffected >= 2.19.0, <= 2.21.6 · fixed in 2.21.7 · GHSA-wv8q-qhhj-9h54
  • com.fasterxml.jackson.core:jackson-databind mavenAffected >= 2.22.0, <= 2.22.2 · fixed in 2.22.3 · GHSA-wv8q-qhhj-9h54
  • tools.jackson.core:jackson-databind mavenAffected >= 3.0.0, <= 3.1.6 · fixed in 3.1.7 · GHSA-wv8q-qhhj-9h54
  • tools.jackson.core:jackson-databind mavenAffected >= 3.2.0, <= 3.2.2 · fixed in 3.2.3 · GHSA-wv8q-qhhj-9h54

[ References ]References