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Full vulnerability report · 2026
CVE-2026-90771High confidence

joi before 17.13.8 and 18.2.9 Prototype Pollution via messages

hapijs · joi

6.3MediumCVSS 4.0
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 16 Sep 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.39% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs hapijs joi and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Open-source package ranges4 source-attributed ranges

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
npmjoi< 17.13.817.13.8GitHub advisory ↗github reviewed aggregator · 5 Oct 2026
npmjoi>= 18.0.0, < 18.2.918.2.9GitHub advisory ↗github reviewed aggregator · 5 Oct 2026
npmjoiSEMVER: introduced 0; fixed 17.13.817.13.8OSV record ↗aggregator derived · 5 Oct 2026
npmjoiSEMVER: introduced 18.0.0; fixed 18.2.918.2.9OSV record ↗aggregator derived · 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

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-2026-90771 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityjoi: joi: Prototype Pollution via custom messages
37 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • gatekeeper/gatekeeper-rhel9 as a component of Gatekeeper 3
  • rhmtc/openshift-migration-ui-rhel8 as a component of Migration Toolkit for Containers
  • rh-podman-desktop.git as a component of Red Hat Build of Podman Desktop
  • redhat-datagrid-maven-repository.zip as a component of Red Hat Data Grid 8
  • grafana as a component of Red Hat Enterprise Linux 10
  • grafana-selinux as a component of Red Hat Enterprise Linux 10
  • grafana.src as a component of Red Hat Enterprise Linux 10
  • grafana as a component of Red Hat Enterprise Linux 8
  • grafana-azure-monitor as a component of Red Hat Enterprise Linux 8
  • grafana-cloudwatch as a component of Red Hat Enterprise Linux 8
  • grafana-elasticsearch as a component of Red Hat Enterprise Linux 8
  • grafana-graphite as a component of Red Hat Enterprise Linux 8
Summary
A flaw was found in joi. This vulnerability, known as prototype pollution, exists in the messages compilation function. A remote attacker can exploit this by supplying specially crafted `__proto__` keys in custom messages. This allows the attacker to manipulate object properties, which could lead to unexpected application behavior or crashes.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

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-2026-76992

No EUVD known-exploited evidence

joi before versions 17.13.8 and 18.2.9 contains a prototype pollution vulnerability in the messages compilation function that accepts __proto__ as an error code. Attackers can supply __proto__ keys in custom messages to replace the returned object's prototype, breaking downstream code relying on Object.prototype methods.

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
6.3 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

joi before versions 17.13.8 and 18.2.9 contains a prototype pollution vulnerability in the messages compilation function that accepts __proto__ as an error code. Attackers can supply __proto__ keys in custom messages to replace the returned object's prototype, breaking downstream code relying on Object.prototype methods.

What

joi before versions 17.13.8 and 18.2.9 contains a prototype pollution vulnerability in the messages compilation function that accepts __proto__ as an error code. Attackers can supply __proto__ keys in custom messages to replace the returned object's prototype, breaking downstream code relying on Object.prototype methods.

Why

The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

joi before versions 17.13.8 and 18.2.9 contains a prototype pollution vulnerability in the messages compilation function that accepts __proto__ as an error code. Attackers can supply __proto__ keys in custom messages to replace the returned object's prototype, breaking downstream code relying on Object.prototype methods.

Why

The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

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.
Reference recorded

CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.

Likely attack path
a network path → Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-1321 ↗

CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'). The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

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.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.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.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VILowVulnerable-system integrity: A successful attack can cause a limited loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.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.
NetworkUnauthenticatedCWE-1321Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-76992Official EUVD mapping

joi before versions 17.13.8 and 18.2.9 contains a prototype pollution vulnerability in the messages compilation function that accepts __proto__ as an error code. Attackers can supply __proto__ keys in custom messages to replace the returned object's prototype, breaking downstream code relying on Object.prototype methods.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260916Security Bulletin 16 Sep 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 16 Sep 2026, published on 16 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
03

Patch and workaround

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.
Patch available
Affected
Fixed
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 13 Sept 2026 · Last source change 24 Sept 2026, 14:21 UTC · CWE-1321 · Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

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 2026-09-14
European sourceENISA EUVD · EUVD-2026-76992
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: removed remediation: access.redhat.com/CVE-2026-90771.
    Before
    remediation: access.redhat.com/CVE-2026-90771
    After
    no authoritative guidance recorded
    CNA ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    joi: 16.0.0 < 17.13.8, 18.0.0 < 18.2.9 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
    After
    joi: 16.0.0 < 17.13.8, 18.0.0 < 18.2.9 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  3. Remediation statusRemediation status changed from Patch available to Awaiting fix.
    Before
    Patch available
    After
    Awaiting fix
    CNA ↗
  4. Affected versionsThe structured affected or fixed version information changed.
    Before
    joi: 16.0.0 < 17.13.8, 18.0.0 < 18.2.9 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    joi: 16.0.0 < 17.13.8, 18.0.0 < 18.2.9 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
    Red Hat Product Security ↗
  5. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
  6. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-90771 to remediation: access.redhat.com/CVE-2026-90771.
    Before
    remediation: access.redhat.com/CVE-2026-90771
    After
    remediation: access.redhat.com/CVE-2026-90771
    Red Hat Product Security ↗
  7. Remediation statusRemediation status changed from Mitigation available to Patch available.
    Before
    Mitigation available
    After
    Patch available
    Red Hat Product Security ↗
  8. Affected versionsThe structured affected or fixed version information changed.
    Before
    gatekeeper/gatekeeper-rhel9 as a component of Gatekeeper 3; rhmtc/openshift-migration-ui-rhel8 as a component of Migration Toolkit for Containers; rh-podman-desktop.git as a component of Red Hat Build of Podman Desktop; redhat-datagrid-maven-repository.zip as a component of Red Hat Data Grid 8; grafana as a component of Red Hat Enterprise Linux 10; grafana-selinux as a component of Red Hat Enterprise Linux 10; grafana.src as a component of Red Hat Enterprise Linux 10; grafana as a component of Red Hat Enterprise Linux 8; grafana-azure-monitor as a component of Red Hat Enterprise Linux 8; grafana-cloudwatch as a component of Red Hat Enterprise Linux 8; grafana-elasticsearch as a component of Red Hat Enterprise Linux 8; grafana-graphite as a component of Red Hat Enterprise Linux 8; grafana-influxdb as a component of Red Hat Enterprise Linux 8; grafana-loki as a component of Red Hat Enterprise Linux 8; grafana-mssql as a component of Red Hat Enterprise Linux 8; grafana-mysql as a component of Red Hat Enterprise Linux 8; grafana-opentsdb as a component of Red Hat Enterprise Linux 8; grafana-pcp as a component of Red Hat Enterprise Linux 8; grafana-pcp.src as a component of Red Hat Enterprise Linux 8; grafana-postgres as a component of Red Hat Enterprise Linux 8; grafana-prometheus as a component of Red Hat Enterprise Linux 8; grafana-selinux as a component of Red Hat Enterprise Linux 8; grafana-stackdriver as a component of Red Hat Enterprise Linux 8; grafana.src as a component of Red Hat Enterprise Linux 8; grafana as a component of Red Hat Enterprise Linux 9; grafana-selinux as a component of Red Hat Enterprise Linux 9; grafana.src as a component of Red Hat Enterprise Linux 9; grafana12.4.src as a component of Red Hat Hardened Images; grafana13.1.src as a component of Red Hat Hardened Images; grafana13.2.src as a component of Red Hat Hardened Images; and 10 more
    After
    gatekeeper/gatekeeper-rhel9 as a component of Gatekeeper 3; rhmtc/openshift-migration-ui-rhel8 as a component of Migration Toolkit for Containers; rh-podman-desktop.git as a component of Red Hat Build of Podman Desktop; redhat-datagrid-maven-repository.zip as a component of Red Hat Data Grid 8; grafana as a component of Red Hat Enterprise Linux 10; grafana-selinux as a component of Red Hat Enterprise Linux 10; grafana.src as a component of Red Hat Enterprise Linux 10; grafana as a component of Red Hat Enterprise Linux 8; grafana-azure-monitor as a component of Red Hat Enterprise Linux 8; grafana-cloudwatch as a component of Red Hat Enterprise Linux 8; grafana-elasticsearch as a component of Red Hat Enterprise Linux 8; grafana-graphite as a component of Red Hat Enterprise Linux 8; grafana-influxdb as a component of Red Hat Enterprise Linux 8; grafana-loki as a component of Red Hat Enterprise Linux 8; grafana-mssql as a component of Red Hat Enterprise Linux 8; grafana-mysql as a component of Red Hat Enterprise Linux 8; grafana-opentsdb as a component of Red Hat Enterprise Linux 8; grafana-pcp as a component of Red Hat Enterprise Linux 8; grafana-pcp.src as a component of Red Hat Enterprise Linux 8; grafana-postgres as a component of Red Hat Enterprise Linux 8; grafana-prometheus as a component of Red Hat Enterprise Linux 8; grafana-selinux as a component of Red Hat Enterprise Linux 8; grafana-stackdriver as a component of Red Hat Enterprise Linux 8; grafana.src as a component of Red Hat Enterprise Linux 8; grafana as a component of Red Hat Enterprise Linux 9; grafana-selinux as a component of Red Hat Enterprise Linux 9; grafana.src as a component of Red Hat Enterprise Linux 9; rhoai/odh-dashboard-rhel9 as a component of Red Hat OpenShift AI (RHOAI); rhoai/odh-mod-arch-automl-rhel9 as a component of Red Hat OpenShift AI (RHOAI); rhoai/odh-mod-arch-autorag-rhel9 as a component of Red Hat OpenShift AI (RHOAI); and 7 more · Fixed: grafana12.4-0:12.4.10-0.3.hum1@aarch64 as a component of Red Hat Hardened Images; grafana12.4-0:12.4.10-0.3.hum1@src as a component of Red Hat Hardened Images; grafana12.4-0:12.4.10-0.3.hum1@x86_64 as a component of Red Hat Hardened Images; grafana13.1-0:13.1.3-0.9.hum1@aarch64 as a component of Red Hat Hardened Images; grafana13.1-0:13.1.3-0.9.hum1@src as a component of Red Hat Hardened Images; grafana13.1-0:13.1.3-0.9.hum1@x86_64 as a component of Red Hat Hardened Images; grafana13.2-0:13.2.1-0.4.hum1@aarch64 as a component of Red Hat Hardened Images; grafana13.2-0:13.2.1-0.4.hum1@src as a component of Red Hat Hardened Images; grafana13.2-0:13.2.1-0.4.hum1@x86_64 as a component of Red Hat Hardened Images
    Red Hat Product Security ↗
  9. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    CVE.org ↗
  10. ENISA EUVD mappingEUVD-2026-76992 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-76992"}
    ENISA EUVD ↗
  11. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
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.
Free version - for non-commercial use only.CVE-2026-90771 · cve.blacktree.nl