GHSA-rmj7-2vxq-3g9f is a high-severity (CVSS 8.1) CWE-184 vulnerability in com.fasterxml.jackson.core:jackson-databind. O3 Security confirms whether GHSA-rmj7-2vxq-3g9f is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
jackson-databind has an array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-rmj7-2vxq-3g9f.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-rmj7-2vxq-3g9f plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
com.fasterxml.jackson.core:jackson-databind☕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
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.
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.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.fasterxml.jackson.core:jackson-databind | ≥ 2.10.0&&< 2.18.8 | 2.18.8 |
| ☕Maven | com.fasterxml.jackson.core:jackson-databind | ≥ 2.19.0&&< 2.21.4 | 2.21.4 |
| ☕Maven | com.fasterxml.jackson.core:jackson-databind | ≥ 3.0.0&&< 3.1.4 | 3.1.4 |
| ☕Maven | tools.jackson.core:jackson-databind | ≥ 3.0.0&&< 3.1.4 | 3.1.4 |
Detection & 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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update com.fasterxml.jackson.core:jackson-databind to 2.18.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rmj7-2vxq-3g9f is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-rmj7-2vxq-3g9f is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-rmj7-2vxq-3g9f. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
This Important flaw in `jackson-databind` allows for a security bypass, enabling arbitrary code execution. The vulnerability arises from insufficient validation of array component types by `BasicPolymorphicTypeValidator`, which permits deserialization of unallowlisted types when processing untrusted input. This bypass…
Frequently Asked Questions
Is GHSA-rmj7-2vxq-3g9f in your dependencies?
O3 detects GHSA-rmj7-2vxq-3g9f across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.