How severe is CVE-2020-8840?

CVE-2020-8840 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-8840?

CVE-2020-8840 affects the following packages: com.fasterxml.jackson.core:jackson-databind (Maven), com.fasterxml.jackson.core:jackson-databind (Maven), com.fasterxml.jackson.core:jackson-databind (Maven), com.fasterxml.jackson.core:jackson-databind (Maven). Ecosystems affected: Maven.

How do I fix CVE-2020-8840?

Update com.fasterxml.jackson.core:jackson-databind to 2.6.7.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-8840 is resolved across your whole dependency graph.

How do I detect CVE-2020-8840 in my Maven dependencies?

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.

How do I mitigate CVE-2020-8840 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2020-8840?

O3 pinpoints whether CVE-2020-8840 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2020-8840 actively exploited in the wild?

Yes. There are 10 known exploit references for CVE-2020-8840, including 5 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What type of vulnerability is CVE-2020-8840?

CVE-2020-8840 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2020-8840 published, and has it been updated?

CVE-2020-8840 was published on February 10, 2020 and was last updated on August 7, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

CRITICAL severity

CVE-2020-8840

CRITICAL

CVE-2020-8840 is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in com.fasterxml.jackson.core:jackson-databind. 10 public exploit references exist, so weaponization risk is real. O3 Security confirms whether CVE-2020-8840 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Deserialization of Untrusted Data in jackson-databind

Also known asGHSA-4w82-r329-3q67

Published

Feb 10, 2020

Updated

Aug 7, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

10 known

Exploitation data as of Aug 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

4 pkgs affected

☕com.fasterxml.jackson.core:jackson-databind☕com.fasterxml.jackson.core:jackson-databind☕com.fasterxml.jackson.core:jackson-databind☕com.fasterxml.jackson.core:jackson-databind

Real-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

FasterXML jackson-databind 2.0.0 through 2.9.10.2 lacks certain xbean-reflect/JNDI blocking, as demonstrated by org.apache.xbean.propertyeditor.JndiConverter.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`com.fasterxml.jackson.core:jackson-databind`	≥ 2.0.0&&< 2.6.7.4	2.6.7.4
☕Maven	`com.fasterxml.jackson.core:jackson-databind`	≥ 2.7.0&&< 2.7.9.7	2.7.9.7
☕Maven	`com.fasterxml.jackson.core:jackson-databind`	≥ 2.8.0&&< 2.8.11.5	2.8.11.5
☕Maven	`com.fasterxml.jackson.core:jackson-databind`	≥ 2.9.0&&< 2.9.10.3	2.9.10.3

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.