GHSA-mhm7-754m-9p8w

jackson-databind: `@JsonView` bypass for creator properties with `@JsonTypeInfo(include=As.EXTERNAL_PROPERTY)`

Published

2026-07-21

Modified

2026-07-21

Sources

github-advisory

Summary

## Summary In `BeanDeserializer.deserializeUsingPropertyBasedWithExternalTypeId`, the active-view (`@JsonView`) filter was applied only to the regular bean-property branch; the creator-property branch performed no `creatorProp.visibleInView(activeView)` check. A constructor parameter annotated with both `@JsonView(RestrictedView.class)` and `@JsonTypeInfo(use=Id.NAME, include=As.EXTERNAL_PROPERTY)` is populated from attacker JSON even when a more restrictive view is active. This is a patch gap. GHSA-5hh8 (CVE-2026-54517) and GHSA-rcqc (CVE-2026-54518) descriptions cover only the main property-based path and the unwrapped-creator path respectively; the external-type-id creator path was fixed on the 3.x line via #6004 ("Extend #5969/#5971 fixes to ... external-type-id case in regular BeanDeserializer", commit 7dc7a17, 2026-05-22) but **the fix was never backported to 2.21 or 2.18**. Users on 2.21.4 and 2.18.8 who upgraded per the published advisories remain vulnerable to the same `@JsonView` bypass technique via a different code path. ## Vulnerable Code Path File: `com/fasterxml/jackson/databind/deser/BeanDeserializer.java` Method: `deserializeUsingPropertyBasedWithExternalTypeId` On 2.21.4 (and 2.18.8), the creator-property branch (around line 1125-1158) checks `creatorProp.isInjectionOnly()` and hands off to `ext.handlePropertyValue(...)` / `buffer.assignParameter(...)` without ever consulting `visibleInView(activeView)`: ```java if (creatorProp != null) { // [databind#1381]: if useInput=FALSE, skip deserialization from input if (creatorProp.isInjectionOnly()) { ... } // NO visibleInView(activeView) CHECK HERE if (!ext.handlePropertyValue(p, ctxt, propName, null)) { if (buffer.assignParameter(creatorProp, ...)) { ... } } continue; } ``` On 3.1.4, the same branch contains the additional guard (commit 7dc7a17): ```java if (creatorProp != null) { // [databind#5971]: must honor active view here too if ((activeView != null) && !creatorProp.visibleInView(activeView)) { p.skipChildren(); continue; } ... } ``` The 2.21 and 2.18 backport PRs (#6005 and #6003) only backported the main-path fixes from #5969/#5971; the external-type-id fix from #6004 was not backported. The maintainer closed #6005 with "got changes merged forward, looks like it's all covered now", but the forward-merge did not include the ExtTypeId creator branch. Proof of Concept Compiles and runs against jackson-databind 2.21.4: ```java import com.fasterxml.jackson.annotation.*; import com.fasterxml.jackson.databind.ObjectMapper; public class JsonViewExternalTypeIdBypass { public static class PublicView {} public static class AdminView extends PublicView {} public static abstract class Asset { public String name; } public static class PublicAsset extends Asset {} public static class AdminAsset extends Asset { public String secret; } public static class Container { @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXTERNAL_PROPERTY, property = "kind") @JsonSubTypes({ @JsonSubTypes.Type(value = PublicAsset.class, name = "pub"), @JsonSubTypes.Type(value = AdminAsset.class, name = "admin") }) @JsonView(AdminView.class) public Asset asset; public String label; @JsonCreator public Container( @JsonProperty("label") String label, @JsonProperty("asset") @JsonView(AdminView.class) Asset asset) { this.label = label; this.asset = asset; } } public static class Wrapper { @JsonView(PublicView.class) public Container data; } public static void main(String[] args) throws Exception { // Admin-only "asset" should be blocked when r

Affected packages

Remediation: Upgrade to 2.18.9 or later.

References

• https://github.com/advisories/GHSA-mhm7-754m-9p8w