Summary
jackson-databind: @JsonView ypassed for @JsonUnwrapped container properties on deserialization
UnwrappedPropertyHandler.processUnwrapped() replays the buffered JSON for a @JsonUnwrapped property by iterating its properties and calling prop.deserializeAndSet() with no prop.visibleInView(ctxt.getActiveView()) guard, the exact guard processUnwrappedCreatorProperties() received in the #5971 / GHSA-rcqc-6cw3-h962 fix, and the guard BeanDeserializer.deserializeWithUnwrapped applies to directly-matched properties. As a result, a property annotated with both @JsonView(PrivilegedView.class) and @JsonUnwrapped is written from attacker JSON even when deserializing under a more-restrictive active view.
Correction to the original framing (runtime-verified): the gap is NOT a per-field inner @JsonView (the unwrapped sub-object's own BeanDeserializer gates inner fields correctly). The unchecked gate is the view of the unwrapped CONTAINER property.
Intent proof (runtime, 2.x HEAD 21dd70dd and 3.x HEAD 7a5939d6)
An @JsonView(AdminView) property that is NOT @JsonUnwrapped → null under PublicView (correctly gated). The identical property WITH @JsonUnwrapped → fully populated (bypass). The fix the creator path already received, not applied to the regular-property method.
Impact, write-side mass-assignment / privilege escalation
@JsonView is commonly used as a write-side authorization guard: a public endpoint binds the body under readerWithView(PublicView.class) and groups privileged state in a nested object whose container property is @JsonView(AdminView). When that property is @JsonUnwrapped, an untrusted caller mass-assigns it. PoC: a self-service registration where AccountFlags{role,approved,creditBalance} is @JsonView(AdminView) @JsonUnwrapped; attacker JSON {role:ADMIN,approved:true,creditBalance:1000000} under PublicView binds all three → approved admin with arbitrary balance. The failing gate is a WRITE gate, hence integrity-high (C:N/I:H/A:N); no worse than the C:L/I:L parent and arguably higher as @JsonView-as-write-guard is the exact use case #5971/#5969 defended.
Affected
com.fasterxml.jackson.core:jackson-databind2.x: confirmed bypass at 21dd70dd (== released 2.21.4 / 2.22.0 line; includes the #5973 backport).DEFAULT_VIEW_INCLUSIONdefault=true.tools.jackson.core:jackson-databind3.x: confirmed bypass at HEAD 7a5939d6 (latest 3.x).DEFAULT_VIEW_INCLUSIONdefault=false → the stock-config repro is the common shape where privileged inner fields are individually@JsonView(PublicView)and the developer relies on the container@JsonView(AdminView); the 3.x PoC mass-assigns role/approved/creditBalance under PublicView. (The other simultaneous report's PoC was reportedly fixed on 3.x; this distinct container-property path is not.)
Additive variants (runtime-confirmed both branches; all closed by the same one-line guard)
- nested
@JsonUnwrapped(unwrapped-in-unwrapped), recursive bypass. - merge /
readerWithView(...).withValueToUpdate(...)(PATCH/partial-update), bypass; non-unwrapped merge control gates correctly. - builder-based deserializer (
@JsonDeserialize(builder=...)),BuilderBasedDeserializerroutes through the sameprocessUnwrapped. - Honest non-findings: read-side serialization correctly honors views (no leak);
@JsonAnySetter+view and@JsonTypeInfo+@JsonUnwrappedare separate/unsupported behaviors, not this bug.
Impact
The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.
CVE-2026-59889 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.21.5, 3.1.5, 2.18.9, 2.22.1, 3.2.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Add prop.visibleInView(ctxt.getActiveView()) (when MapperFeature.DEFAULT_VIEW_INCLUSION/active-view applies) to the processUnwrapped() property loop, mirroring processUnwrappedCreatorProperties(). One change closes the impact PoC + all three variants across BeanDeserializer and BuilderBasedDeserializer. Full runnable PoCs (2.x + 3.x) + variant harnesses available on request.
Frequently Asked Questions
- What is CVE-2026-59889? CVE-2026-59889 is a medium-severity incorrect authorization vulnerability in com.fasterxml.jackson.core:jackson-databind (maven), affecting versions >= 2.21.0, < 2.21.5. It is fixed in 2.21.5, 3.1.5, 2.18.9, 2.22.1, 3.2.1. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
- How severe is CVE-2026-59889? CVE-2026-59889 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2026-59889?
com.fasterxml.jackson.core:jackson-databind(maven) (versions >= 2.21.0, < 2.21.5)tools.jackson.core:jackson-databind(maven) (versions >= 3.0.0, <= 3.1.4)
- Is there a fix for CVE-2026-59889? Yes. CVE-2026-59889 is fixed in 2.21.5, 3.1.5, 2.18.9, 2.22.1, 3.2.1. Upgrade to this version or later.
- Is CVE-2026-59889 exploitable, and should I be worried? Whether CVE-2026-59889 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-59889 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-59889?
- Upgrade
com.fasterxml.jackson.core:jackson-databindto 2.21.5 or later - Upgrade
tools.jackson.core:jackson-databindto 3.1.5 or later - Upgrade
com.fasterxml.jackson.core:jackson-databindto 2.18.9 or later - Upgrade
com.fasterxml.jackson.core:jackson-databindto 2.22.1 or later - Upgrade
tools.jackson.core:jackson-databindto 3.2.1 or later
- Upgrade