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CVE Record

CVE-2026-33210: Ruby JSON has a format string injection vulnerability

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.

CriticalCVSS 9.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

A vulnerable Ruby JSON library version can mishandle attacker-supplied JSON when duplicate-key rejection is enabled. In affected applications, this can crash service or expose sensitive process information. The issue is patched, but exposure depends on a specific parsing option and untrusted input path.

Executive priority

Treat this as urgent for internet-facing Ruby services that parse customer-supplied JSON. The vulnerability is rated critical and patched, but actual business risk is concentrated in code paths using duplicate-key rejection on untrusted input.

Technical view

CVE-2026-33210 is a CWE-134 format string injection in Ruby json versions 2.14.0 through affected 2.15, 2.17, and 2.19 branches. It applies when JSON.parse-style handling uses allow_duplicate_key: false on user-supplied documents. CVSS 3.1 is 9.1 with high confidentiality and availability impact.

Likely exposure

Likely exposure is Ruby applications or packaged products using the vulnerable json gem versions and parsing externally supplied JSON with allow_duplicate_key: false. Dependency managers, bundled gems, containers, and Red Hat packages should be checked. Applications not using that option may not meet the described trigger condition.

Exploitation context

The source bundle does not show CISA KEV listing or cited active exploitation. Public sources describe network-reachable, unauthenticated exploitation potential only where the vulnerable parser path processes attacker-controlled JSON with the affected option enabled.

Researcher notes

The key research question is reachability: vulnerable version alone is insufficient without the allow_duplicate_key: false parsing option and attacker-controlled documents. Sources identify denial of service and information disclosure, but do not provide evidence of active exploitation in the supplied bundle.

Mitigation direction

  • Upgrade ruby/json to 2.15.2.1, 2.17.1.2, 2.19.2, or later.
  • Apply applicable Red Hat security advisories for packaged Ruby JSON components.
  • Prioritize services that parse untrusted JSON with allow_duplicate_key: false.
  • Check vendor guidance before relying on configuration-only workarounds.
  • Rebuild and redeploy containers or packages that vendor the vulnerable gem.

Validation and detection

  • Inventory json gem versions in application manifests, lockfiles, images, and runtime environments.
  • Search code for allow_duplicate_key: false in JSON parsing paths.
  • Map those parser paths to public APIs, webhooks, uploads, and message consumers.
  • Confirm runtime loads the patched json version after deployment.
  • Review Red Hat errata applicability for managed operating system packages.
Prepared
Confidence
high
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-134: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-33210 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
7Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.1CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H3.95.2redhat-SADP
8.3CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N——GitHub_M

Vulnerability scoring details

Base CVSS 4.0 score

8.3High
CVSS 4.0 vector shape for CVE-2026-33210Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPruby/json: Ruby JSON: Denial of Service or Information Disclosure via format string injection
other:Red Hat severity ratingcvssV3_1
  • 2026-03-21T00:01:40.435Z: Reported to Red Hat.
  • 2026-03-20T22:57:08.758Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
rubyjson>= 2.14.0, < 2.15.2.1, >= 2.16.0, < 2.17.1.2, >= 2.18.0, < 2.19.2Listed
Weakness

CWE details

CWE-134

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-134 · source CWE mapping

Use of Externally-Controlled Format String

Use of Externally-Controlled Format String represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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