How severe is GHSA-gg4h-3hg2-grpc?

GHSA-gg4h-3hg2-grpc has a CVSS score of 3.7/10, rated LOW. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-gg4h-3hg2-grpc?

GHSA-gg4h-3hg2-grpc affects the following packages: joi (npm), joi (npm). Ecosystems affected: npm.

How do I fix GHSA-gg4h-3hg2-grpc?

Update joi to 17.13.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gg4h-3hg2-grpc is resolved across your whole dependency graph.

How do I detect GHSA-gg4h-3hg2-grpc in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for joi, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-gg4h-3hg2-grpc if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is GHSA-gg4h-3hg2-grpc actively exploited in the wild?

No public exploit code has been indexed for GHSA-gg4h-3hg2-grpc yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-gg4h-3hg2-grpc?

GHSA-gg4h-3hg2-grpc has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 32th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-gg4h-3hg2-grpc?

GHSA-gg4h-3hg2-grpc is classified as CWE-1321 (CWE-1321). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-gg4h-3hg2-grpc published, and has it been updated?

GHSA-gg4h-3hg2-grpc was published on September 8, 2026 and was last updated on September 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

LOW severity

joi: object().rename() with a template target can set the validated object's prototypeGHSA-gg4h-3hg2-grpc

LOWFix: hapijs/joi#3134

GHSA-gg4h-3hg2-grpc is a low-severity (CVSS 3.7) CWE-1321 vulnerability in joi. A fix is available for joi — see the affected versions and patch details below.

Also known asCVE-2026-84367

Published

Sep 8, 2026

Updated

Sep 8, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-gg4h-3hg2-grpc.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs32th percentile — riskier than 32% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-gg4h-3hg2-grpc by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

14Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

joinpm

15.7Mdownloads / week

Description

Impact

Applications are affected only if a schema renames keys with a regular-expression source and a Joi.expression() / Joi.x() target that interpolates the pattern's own match data, combined with { multiple: true }, for example .rename(/^x-(.+)$/, Joi.x('{#1}'), { multiple: true }). Because the target is rendered from the matched input key, an attacker who controls input keys can send x-__proto__ with an object value and make the rename target render as __proto__, which sets the prototype of the object joi returns instead of creating a key on it. The global Object.prototype is not modified, so the effect is confined to the object returned by that one validate() call.

Schemas using a static string rename target are not affected, and neither are schemas left on the default { multiple: false }.

Patches

Versions 17.13.5 and 18.2.4 have been released to address the issue.

Workarounds

Replace the template rename target with a static string target.
Keep the template but make the capture unable to produce __proto__, using a negative lookahead: .rename(/^x-(?!__proto__$)(.+)$/, Joi.x('{#1}'), { multiple: true })
Drop { multiple: true } from the rename, which stops the rename before the assignment.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`joi`	≥ 16.0.0&&< 17.13.5	17.13.5`npm install joi@17.13.5`
📦npm	`joi`	≥ 18.0.0&&< 18.2.4	18.2.4`npm install joi@18.2.4`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for joi, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update joi to 17.13.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gg4h-3hg2-grpc is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact Applications are affected only if a schema renames keys with a regular-expression source and a `Joi.expression()` / `Joi.x()` target that interpolates the pattern's own match data, combined with `{ multiple: true }`, for example `.rename(/^x-(.+)$/, Joi.x('{#1}'), { multiple: true })`. Because the target is rendered from the matched input key, an attacker who controls input keys can send `x-__proto__` with an object value and make the rename target render as `__proto__`, which sets the prototype of the object joi returns instead of creating a key on it. The global `Object.prototype