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CVE-2026-54512 high CVSS 8.1

Vulnerability in com.fasterxml.jackson.core:jackson-databind (CVE-2026-54512)

Summary

Vulnerability in com.fasterxml.jackson.core:jackson-databind (CVE-2026-54512). Successful exploitation can lead to full system takeover. Exploitable via PolymorphicTypeValidator. Mitigation: upgrade to 2.21.4 or later.

Original description

The description as published by the source.

jackson-databind's PolymorphicTypeValidator (PTV) is the primary safety mechanism guarding polymorphic deserialization. When polymorphic typing is enabled and a type identifier contains generic parameters (i.e. the type ID string contains <), DatabindContext._resolveAndValidateGeneric() validates only the raw container class name (the substring before <) against the configured PTV.

If the container type is approved, the method parses the full canonical type string via TypeFactory.constructFromCanonical() and returns the fully parameterized type without ever validating the nested type arguments against the PTV. The nested type arguments are then resolved, instantiated, and populated as beans during deserialization.

An attacker who controls the type ID can therefore place a denied class as a generic type parameter of an allowed container — for example java.util.ArrayList when only java.util.ArrayList is allow-listed. The container passes the PTV check; com.evil.Gadget is loaded via Class.forName(name, true, loader), instantiated, and its properties are set from attacker-controlled JSON. This completely bypasses an explicitly configured PTV allow-list.

This is the same vulnerability class responsible for the historical sequence of jackson-databind deserialization CVEs; here it manifests as a validator bypass rather than a missing deny-list entry.

Impact

  • Bypass of the PTV allow-list, including the recommended `BasicPolymorphicTypeValidato…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-54512 has been found in com.fasterxml.jackson.core:jackson-databind.
Attackers can target a specific entry point like PolymorphicTypeValidator over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.1/10.
What to do: upgrade com.fasterxml.jackson.core:jackson-databind to 2.21.4 or later.
If unsure, ask your IT team or search "com.fasterxml.jackson.core:jackson-databind CVE-2026-54512" on the vendor's site.

CVE-2026-54512 (com.fasterxml.jackson.core:jackson-databind) — CWE-184 / CVSS v3 8.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: PolymorphicTypeValidator / java.util.ArrayList / com.evil.Gadget / BasicPolymorphicTypeValidator
Patched: 2.21.4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-184) exists in com.fasterxml.jackson.core:jackson-databind. Attackers reach the vulnerable code path via PolymorphicTypeValidator without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of com.fasterxml.jackson.core:jackson-databind. Attack surface: PolymorphicTypeValidator / java.util.ArrayList / com.evil.Gadget / BasicPolymorphicTypeValidator.

🔥 Severity

Severity: High (CVSS 8.1/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 2.21.4.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで com.fasterxml.jackson.core:jackson-databind を使っているサービスとバージョンを洗い出す。

  2. 2
    Apply patch patch 
    Upgrade com.fasterxml.jackson.core:jackson-databind to 2.21.4

    ステージング環境で 2.21.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

maven com.fasterxml.jackson.core:jackson-databind
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.21.4"}]}]
maven tools.jackson.core:jackson-databind
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.4"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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