Ruby JSON has a format string injection vulnerability
ruby · json
8.3HighCVSS 4.0
Recommended action
Within 7 days
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch available
Distribution package intelligence
Ubuntu vendor package status
Canonical’s release and source-package findings are shown separately from local repository availability.
1 package state
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
Ubuntu release
Source package
Vendor state
Fixed version
Evidence
Ubuntu 24.04 LTSnoble · standard archive
ruby-json
Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
1 current
CVE-2026-33210 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityruby/json: Ruby JSON: Denial of Service or Information Disclosure via format string injection
181 fixed
The vendor explicitly identifies these products or versions as containing the fix.
ruby4.0-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-0:4.0.3-34.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-debuginfo-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-debuginfo-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-debuginfo-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-debuginfo-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-debugsource-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-debugsource-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10)
ruby4.0-debugsource-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10)
Summary
A flaw was found in Ruby JSON. This vulnerability, a format string injection, allows a remote attacker to cause a denial of service (DoS) or disclose sensitive information. The flaw occurs when processing specially crafted user-supplied documents with the allow_duplicate_key: false parsing option enabled.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Optional official sources
National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.
Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.
Official European source
ENISA European Vulnerability Database
Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.
1 current
ENISA EUVD identifier
EUVD-2026-13875
No EUVD known-exploited evidence
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.
EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
8.3 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch available
01
What, why and how
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.
What
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.
Why
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may obtain information outside the intended access boundary.
What
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.
Why
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may obtain information outside the intended access boundary.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No confirmed evidence
No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.None recorded
No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
Likely attack path
a network path → Use of Externally-Controlled Format String → obtain information outside the intended access boundary
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness ?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-134: Use of Externally-Controlled Format String. The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
CVSS vector ?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATPresentAttack requirements: A particular deployment or execution condition must be present.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCLowVulnerable-system confidentiality: A successful attack can cause a limited loss.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-134
A
Official authority intelligence
Only matched European and national findings are included. Language selectors and unavailable sources are omitted.
ENISA EUVD · EUVD-2026-13875Official EUVD mapping
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.
Operational remediation based on structured source evidence.
Status ?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
ruby4.0-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-debuginfo-0:1.6.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); and 151 more
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Workaround
A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04
Evidence and provenance
Published 20 Mar 2026 · Last source change 21 Aug 2026, 12:13 UTC · CWE-134 · Use of Externally-Controlled Format String
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source ?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-13875
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Vendor guidanceAuthoritative vendor guidance changed from authoritative remediation link · mitigation, vendor advisory to authoritative remediation link · mitigation.
Before
authoritative remediation link · mitigation, vendor advisory
Vendor guidanceAuthoritative vendor guidance changed from authoritative remediation link · mitigation to authoritative remediation link · mitigation, vendor advisory.
Before
authoritative remediation link · mitigation
After
authoritative remediation link · mitigation, vendor advisory
Affected versionsThe structured affected or fixed version information changed.
Before
ruby4.0.src as a component of Red Hat Hardened Images · Fixed: ruby4.0-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-debuginfo-0:1.6.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); and 147 more
After
Fixed: ruby4.0-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debuginfo-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-debugsource-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-devel-0:4.0.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-0:0.5.7-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-mysql2-debuginfo-0:0.5.7-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-0:1.6.3-34.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); ruby4.0-rubygem-pg-debuginfo-0:1.6.3-34.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); and 151 more
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
CVE-2026-33210: Ruby JSON has a format string injection vulnerability | BlackTree
