Cyber Resilience

CVE-2026-33210

Ruby-Lang Json 2.14.0 – 2.15.2.1

Published
20 March 2026
Modified
21 July 2026
Patch / advisory
View advisory
CVSS Score v4 8.3
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0084 55th percentile
Risk Priority 45 floored blend · peak EPSS

Summary

CVE-2026-33210 is a high-severity Use of Externally-Controlled Format String (CWE-134) vulnerability in Ruby-Lang Json. Its CVSS base score is 8.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 45% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-33210 is a format string injection vulnerability (CWE-134) in Ruby JSON, a JSON implementation for the Ruby programming language. It affects versions from 2.14.0 up to but not including 2.15.2.1, 2.17.1.2, and 2.19.2. The flaw arises when parsing user-supplied JSON documents with the allow_duplicate_key: false option enabled, potentially leading to denial of service or information disclosure. The vulnerability carries a CVSS v3.1 base score of 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H), indicating critical severity due to its network accessibility and high impact on confidentiality and availability.

Remote attackers require no privileges or user interaction to exploit this issue. By supplying specially crafted JSON input to applications using the vulnerable Ruby JSON versions with the specified parsing option, adversaries can inject format strings, resulting in either denial of service through crashes or resource exhaustion, or leakage of sensitive memory contents.

The issue has been patched in Ruby JSON versions 2.15.2.1, 2.17.1.2, and 2.19.2. Security practitioners should prioritize upgrading affected dependencies to these versions. Additional details are available in the GitHub security advisory at https://github.com/ruby/json/security/advisories/GHSA-3m6g-2423-7cp3.

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-134

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-27820Same vendor: Ruby-Lang
CVE-2025-27788Same vendor: Ruby-Lang
CVE-2023-24590Shared CWE-134
CVE-2025-48730Shared CWE-134
CVE-2024-4641Shared CWE-134
CVE-2025-40600Shared CWE-134
CVE-2023-6764Shared CWE-134
CVE-2023-21497Shared CWE-134
CVE-2025-46123Shared CWE-134
CVE-2024-6145Shared CWE-134

Affected Assets

ruby-lang
json
2.14.0 — 2.15.2.1 · 2.16.0 — 2.17.1.2 · 2.18.0 — 2.19.2

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and static analysis can discover format-string vulnerabilities before deployment.

SI-10 Information Input Validation good match

Input validation can reject or sanitize externally supplied format strings before they reach formatting functions.

SA-15 Development Process, Standards, and Tools partial match

Secure development standards and tools can mandate use of static format strings or safe formatting APIs.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent external format strings via code review, static analysis, and safe APIs.

ID.RA-01 partial match
prevents

Vulnerability identification can discover existing format-string flaws but does not prevent their introduction.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect format-string vulnerabilities before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates input validation and safe API usage that can prevent externally-controlled format strings.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify safe formatting functions and ban uncontrolled format strings.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles discourage dangerous string-handling patterns that lead to format-string issues.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly forbid the use of untrusted format strings and prescribe safe alternatives.

References