jackson-databind's renamed @JsonIgnore'd setters can deserialize via private fieldsGHSA-9fxm-vc8v-hj55
MEDIUMFix: FasterXML/jackson-databind#5967GHSA-9fxm-vc8v-hj55 is a medium-severity (CVSS 5.3) CWE-915 vulnerability in com.fasterxml.jackson.core:jackson-databind. A fix is available for com.fasterxml.jackson.core:jackson-databind — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-9fxm-vc8v-hj55.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-9fxm-vc8v-hj55 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
com.fasterxml.jackson.core:jackson-databind☕com.fasterxml.jackson.core:jackson-databind☕tools.jackson.core:jackson-databindReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Summary
POJOPropertiesCollector._renameProperties() allows a property with @JsonProperty("renamed") on the getter and @JsonIgnore on the setter to be renamed rather than dropped. With MapperFeature.INFER_PROPERTY_MUTATORS enabled (default), the private backing field is retained; during deserialization BeanDeserializerFactory.addBeanProps() sees hasField()==true, builds a FieldProperty, and makes the backing field writable. An attacker supplying the renamed JSON key writes the backing field directly, bypassing the @JsonIgnore on the setter.
Impact
POJOs combining a renamed getter with an ignored setter (a read-only-over-the-wire pattern) have that field silently set from attacker input (property tampering / mass assignment). Not a general gadget; no RCE.
Affected / Patched (verified via git tag --contains)
- 2.21 line:
>= 2.21.0, < 2.21.4-> fixed in 2.21.4 (backportc3d56dd, #5968) - 3.x line:
>= 3.0.0, < 3.1.4-> fixed in 3.1.4 (#5967,e88cb17)
Severity / CWE
Maintainer: minor. Reporter: HIGH. CWE-915.
Credits
Omkhar Arasaratnam (@omkhar) - finder.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.fasterxml.jackson.core:jackson-databind | ≥ 2.21.0&&< 2.21.4 | 2.21.4com.fasterxml.jackson.core:jackson-databind:2.21.4 |
| ☕Maven | com.fasterxml.jackson.core:jackson-databind | ≥ 3.0.0&&< 3.1.4 | 3.1.4com.fasterxml.jackson.core:jackson-databind:3.1.4 |
| ☕Maven | tools.jackson.core:jackson-databind | ≥ 3.0.0&&< 3.1.4 | 3.1.4tools.jackson.core:jackson-databind:3.1.4 |
Affected Products
jackson-databindfasterxmlDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.fasterxml.jackson.core:jackson-databind, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.fasterxml.jackson.core:jackson-databind to 2.21.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9fxm-vc8v-hj55 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Moderate: This flaw in jackson-databind allows for property tampering and mass assignment in Red Hat products. When `MapperFeature.INFER_PROPERTY_MUTATORS` is enabled by default, an attacker can bypass `@JsonIgnore` annotations on setters by supplying a renamed JSON key, directly writing to private backing fields and…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for GHSA-9fxm-vc8v-hj55 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat build of Quarkus 3.27.4.SP2 | com.fasterxml.jackson.core/jackson-databind:2.21.4.redhat-00002 | RHSA-2026:36002 |
| Red Hat build of Quarkus 3.33.2.SP2 | com.fasterxml.jackson.core/jackson-databind:2.21.4.redhat-00002 | RHSA-2026:36013 |
Frequently Asked Questions
Is GHSA-9fxm-vc8v-hj55 in your dependencies?
Find it across Maven, including transitive dependencies.