How severe is CVE-2026-90771?

No CVSS score has been assigned to CVE-2026-90771 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-90771?

CVE-2026-90771 affects the following packages: joi (npm), joi (npm). Ecosystems affected: npm.

How do I fix CVE-2026-90771?

Update joi to 17.13.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-90771 is resolved across your whole dependency graph.

How do I detect CVE-2026-90771 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 CVE-2026-90771 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 CVE-2026-90771 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-90771 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 CVE-2026-90771?

CVE-2026-90771 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 CVE-2026-90771?

CVE-2026-90771 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 CVE-2026-90771 published, and has it been updated?

CVE-2026-90771 was published on September 13, 2026 and was last updated on October 21, 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

CVE-2026-90771 — joi

Fix: hapijs/joi@5b8333c

CVE-2026-90771 is a CWE-1321 vulnerability in joi. A fix is available for joi — see the affected versions and patch details below.

joi before 17.13.8 and 18.2.9 Prototype Pollution via messages

Also known asGHSA-wr44-6hxh-3jwq

Published

Sep 13, 2026

Updated

Oct 21, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-90771.

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.

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

14.6Mdownloads / week

Description

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.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`joi`	all versions	17.13.8`npm install joi@17.13.8`
📦npm	`joi`	≥ 18.0.0&&< 18.2.9	18.2.9`npm install joi@18.2.9`

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 17.13.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-90771 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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

A flaw in joi permits prototype manipulation when attacker-controlled JSON or configuration containing __proto__ is supplied to the .messages() or .prefs() APIs, potentially disrupting downstream application behavior.

Workaround published by Red Hat

Upgrade joi to 17.13.8, 18.2.9, or later. Avoid passing untrusted data to Joi message configuration until upgraded.

Source: Red Hat security advisory for CVE-2026-90771 (CC BY 4.0)

Product	Fixed in	Advisory
Red Hat Hardened Images	`grafana13-1-main-13.1.3-0.9.hum1`	RHSA-2026:67573
Red Hat Hardened Images	`grafana13-2-main-13.2.1-0.4.hum1`	RHSA-2026:67605
Red Hat Hardened Images	`grafana12-4-main-12.4.10-0.3.hum1`	RHSA-2026:67610

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

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