How severe is CVE-2026-33210?

CVE-2026-33210 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.

Is CVE-2026-33210 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33210?

CVE-2026-33210 affects Ruby-lang Json. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33210?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-33210 have an EU (EUVD) identifier?

Yes. CVE-2026-33210 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13875.

When was CVE-2026-33210 published?

CVE-2026-33210 was published on 2026-03-20 and last updated on 2026-06-30.

CVE-2026-33210

CVE-2026-33210 is a critical-severity vulnerability in Ruby-lang Json with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-134.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v4: 8.3
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-13875
Weakness: CWE-134
Affected product: Ruby-lang Json
Published: 2026-03-20
Last modified: 2026-06-30

Description

Ruby JSON is a JSON implementation for Ruby. From version 2.14.0 to before versions 2.15.2.1, 2.17.1.2, and 2.19.2, a format string injection vulnerability can lead to denial of service attacks or information disclosure, when the allow_duplicate_key: false parsing option is used to parse user supplied documents. This issue has been patched in versions 2.15.2.1, 2.17.1.2, and 2.19.2.

Frequently asked questions

What is CVE-2026-33210?: Ruby JSON is a JSON implementation for Ruby. From version 2.14.0 to before versions 2.15.2.1, 2.17.1.2, and 2.19.2, a format string injection vulnerability can lead to denial of service attacks or information disclosure, when the allow_duplicate_key: false parsing option is used to parse user supplied documents. This issue has been patched in versions 2.15.2.1, 2.17.1.2, and 2.19.2.
How severe is CVE-2026-33210?: CVE-2026-33210 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2026-33210 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33210?: CVE-2026-33210 affects Ruby-lang Json. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33210?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-33210 have an EU (EUVD) identifier?: Yes. CVE-2026-33210 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13875.
When was CVE-2026-33210 published?: CVE-2026-33210 was published on 2026-03-20 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:ruby-lang:json:*:*:*:*:*:ruby:*:*

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