How severe is CVE-2020-10663?

CVE-2020-10663 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-10663?

CVE-2020-10663 affects the following packages: json (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2020-10663?

Update json to 2.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-10663 is resolved across your whole dependency graph.

How do I detect CVE-2020-10663 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for json, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-10663 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.

Is CVE-2020-10663 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2020-10663, including 1 in-the-wild exploitation 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 is the EPSS score for CVE-2020-10663?

CVE-2020-10663 has an EPSS (Exploit Prediction Scoring System) score of 6.8%, placing it in the 94th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-10663?

CVE-2020-10663 is classified as Improper Input Validation (CWE-20). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-10663 published, and has it been updated?

CVE-2020-10663 was published on April 28, 2020 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

HIGH severity

CVE-2020-10663 — json

HIGH

CVE-2020-10663 is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in json. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for json — see the affected versions and patch details below.

Unsafe object creation in json RubyGem

Also known asGHSA-jphg-qwrw-7w9g

Published

Apr 28, 2020

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

2 known

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

6.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs94th percentile — riskier than 94% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

💎json

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

The JSON gem through 2.2.0 for Ruby, as used in Ruby 2.4 through 2.4.9, 2.5 through 2.5.7, and 2.6 through 2.6.5, has an Unsafe Object Creation Vulnerability. This is quite similar to CVE-2013-0269, but does not rely on poor garbage-collection behavior within Ruby. Specifically, use of JSON parsing methods can lead to creation of a malicious object within the interpreter, with adverse effects that are application-dependent.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`json`	all versions	2.3.0`bundle update json --conservative`

Affected Products

5 products · 7 configurations

macosapple

1 version

11.0.1

debian linuxdebian

2 versions

8.010.0

fedorafedoraproject

2 versions

3031

Application

jsonjson_project

≤ 2.2.0

range

leapopensuse

1 version

15.1

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.

The JSON gem through 2.2.0 for Ruby, as used in Ruby 2.4 through 2.4.9, …

github.comGithubMar 2020

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for json, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update json to 2.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-10663 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.

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.

Red HatModerate

Red Hat CloudForms 5 uses vulnerable rubygem-json, however, is not vulnerable in Ruby since it does not use version which includes JSON into stdlib. This issue affects the version of JSON(embedded in pcs) as shipped with Red Hat Gluster Storage 3. However, the vulnerable method calls are currently not used by the…

Workaround published by Red Hat

To mitigate this vulnerability, do not supply untrusted user input and/or untrusted strings to the following method calls or utilize code libraries which do so: ``` JSON(user_input) JSON[user_input, nil] JSON.parse(user_input, nil) JSON::Parser.new(user_input).parse ``` Also note that JSON.load() should never be given input from unknown sources.

Source: Red Hat security advisory for CVE-2020-10663 (CC BY 4.0)

Product	Fixed in	Advisory
Red Hat Enterprise Linux 8	`ruby:2.5-8040020200923213910.522a0ee4`	RHSA-2021:2587
Red Hat Enterprise Linux 8	`ruby:2.6-8040020210430142949.522a0ee4`	RHSA-2021:2588
Red Hat Enterprise Linux 8	`pcs-0:0.10.4-6.el8_2.1`	RHSA-2020:2462
Red Hat Enterprise Linux 8.0 Update Services for SAP Solutions	`pcs-0:0.10.1-4.el8_0.5`	RHSA-2020:2473
Red Hat Enterprise Linux 8.1 Extended Update Support	`pcs-0:0.10.2-4.el8_1.1`	RHSA-2020:2670
Red Hat Enterprise Linux 8.1 Update Services for SAP Solutions	`ruby:2.6-8010020220201152941.c27ad7f8`	RHSA-2022:0581
Red Hat Enterprise Linux 8.2 Extended Update Support	`ruby:2.6-8020020220201131207.4cda2c84`	RHSA-2022:0582
Red Hat Software Collections for Red Hat Enterprise Linux 7	`rh-ruby25-ruby-0:2.5.9-9.el7`	RHSA-2021:2104

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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