Summary
jackson-databind has an array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)
BasicPolymorphicTypeValidator.Builder.allowIfSubTypeIsArray() allowlists any array type based only on clazz.isArray(), without validating the array's component (element) type against the configured allowlist. A PTV built with allowIfSubTypeIsArray() plus an explicit concrete-type allowlist therefore still permits EvilType[] even though EvilType is not allowlisted. When Jackson deserializes the elements and no per-element type IDs are present, it instantiates the component type directly with no further PTV check, bypassing the allowlist.
Affected / Patched (verified via git tag --contains)
- 2.18 line:
>= 2.10.0, < 2.18.8-> fixed in 2.18.8 - 2.19-2.21 line:
>= 2.19.0, < 2.21.4-> fixed in 2.21.4 - 3.x line:
>= 3.0.0, < 3.1.4-> fixed in 3.1.4
PolymorphicTypeValidator was added in 2.10.0 so vulnerability N/A for versions prior to that.
Severity / CWE
Maintainer: significant. Reporter: HIGH. CWE-184 (Incomplete List of Disallowed Inputs); related CWE-502.
Upstream fix
FasterXML/jackson-databind#5981; fix PR #5983 (24529da), 2.18 backport PR #5984 (01d1692). Released 2026-06-04 in 2.18.8 / 2.21.4 / 3.1.4.
Credits
Omkhar Arasaratnam (@omkhar) - finder.
Impact
Applications using BasicPolymorphicTypeValidator with allowIfSubTypeIsArray() as a safeguard get no protection for concrete array component types; an attacker controlling JSON can instantiate non-allowlisted types via an array wrapper, re-opening the gadget-instantiation risk PTV is meant to prevent.
CVE-2026-54513 has a CVSS score of 8.1 (High). The vector is network-reachable, no 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 (2.18.8, 2.21.4, 3.1.4); 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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com.fasterxml.jackson.core:jackson-databind to 2.18.8 or later; com.fasterxml.jackson.core:jackson-databind to 2.21.4 or later; com.fasterxml.jackson.core:jackson-databind to 3.1.4 or later; tools.jackson.core:jackson-databind to 3.1.4 or later
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Frequently Asked Questions
- What is CVE-2026-54513? CVE-2026-54513 is a high-severity security vulnerability in com.fasterxml.jackson.core:jackson-databind (maven), affecting versions >= 2.10.0, < 2.18.8. It is fixed in 2.18.8, 2.21.4, 3.1.4.
- How severe is CVE-2026-54513? CVE-2026-54513 has a CVSS score of 8.1 (High). 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-2026-54513?
com.fasterxml.jackson.core:jackson-databind(maven) (versions >= 2.10.0, < 2.18.8)tools.jackson.core:jackson-databind(maven) (versions >= 3.0.0, < 3.1.4)
- Is there a fix for CVE-2026-54513? Yes. CVE-2026-54513 is fixed in 2.18.8, 2.21.4, 3.1.4. Upgrade to this version or later.
- Is CVE-2026-54513 exploitable, and should I be worried? Whether CVE-2026-54513 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-2026-54513 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-2026-54513?
- Upgrade
com.fasterxml.jackson.core:jackson-databindto 2.18.8 or later - Upgrade
com.fasterxml.jackson.core:jackson-databindto 2.21.4 or later - Upgrade
com.fasterxml.jackson.core:jackson-databindto 3.1.4 or later - Upgrade
tools.jackson.core:jackson-databindto 3.1.4 or later
- Upgrade