How severe is CVE-2026-44291?

CVE-2026-44291 has a CVSS score of 8.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-44291?

CVE-2026-44291 affects the following packages: protobufjs (npm), protobufjs (npm). Ecosystems affected: npm.

How do I fix CVE-2026-44291?

Update protobufjs to 7.5.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44291 is resolved across your whole dependency graph.

How do I detect CVE-2026-44291 in my npm dependencies?

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

How do I mitigate CVE-2026-44291 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2026-44291 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-44291 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-2026-44291?

CVE-2026-44291 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 43th 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-2026-44291?

CVE-2026-44291 is classified as Code Injection (CWE-94). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-44291 published, and has it been updated?

CVE-2026-44291 was published on May 13, 2026 and was last updated on October 28, 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

HIGH severity

CVE-2026-44291 — protobufjs

HIGH

CVE-2026-44291 is a high-severity (CVSS 8.1) Code Injection vulnerability in protobufjs. A fix is available for protobufjs — see the affected versions and patch details below.

protobufjs: Code generation gadget after prototype pollution

Also known asGHSA-75px-5xx7-5xc7

Published

May 13, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
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 CVE-2026-44291.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs43th percentile — riskier than 43% of all scored CVEsHighest risk

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

How urgent is this, really

Where this sits among everything scored

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.

6Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

protobufjsnpm

123.5Mdownloads / week

Description

Summary

protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If Object.prototype had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information.

This could cause attacker-controlled strings to be emitted into generated JavaScript code.

Impact

An attacker who can first trigger a prototype pollution vulnerability may be able to influence generated protobufjs encode or decode functions in a way that can lead to arbitrary JavaScript execution.

This issue requires a separate prototype pollution primitive before protobufjs is invoked.

Applications without a reachable prototype pollution primitive are not directly exploitable through this issue alone.

Preconditions

The application or one of its dependencies must allow an attacker to pollute Object.prototype.
The polluted property must affect protobufjs internal type lookup behavior.
The application must use protobufjs functionality that generates encode or decode code for affected types.
The generated code path must be reached after the prototype pollution has occurred.

Workarounds

Avoid running affected versions in applications where attacker-controlled input can pollute Object.prototype. If immediate upgrade is not possible, remove or mitigate reachable prototype pollution primitives and isolate schema/message processing from untrusted application state.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`protobufjs`	all versions	7.5.6`npm install protobufjs@7.5.6`
📦npm	`protobufjs`	≥ 8.0.0&&< 8.0.2	8.0.2`npm install protobufjs@8.0.2`

Affected Products

1 product · 2 configurations

Application

protobufjsprotobufjs_project

≥ 8.0.0 && < 8.0.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for protobufjs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update protobufjs to 7.5.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44291 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

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 HatImportant

This Important flaw in protobufjs, a JavaScript library, potentially enables arbitrary code execution when a separate prototype pollution vulnerability is present in an application. Exploitation requires an attacker to first pollute `Object.prototype` and then trigger protobufjs functionality that generates encode or…

Workaround published by Red Hat

Mitigation involves preventing prototype pollution within applications that utilize protobufjs. Administrators should ensure that untrusted input cannot pollute `Object.prototype` in the application or its dependencies. Additionally, isolating schema and message processing from untrusted application states can prevent attacker-controlled properties from being resolved as valid protobuf type information.

Source: Red Hat security advisory for CVE-2026-44291 (CC BY 4.0)

Product	Fixed in	Advisory
Cryostat 4 on RHEL 9	`cryostat/cryostat-grafana-dashboard-rhel9:4.2.0-13`	RHSA-2026:48151
Red Hat Ansible Automation Platform 2.2	`ansible-automation-platform/automation-portal:1784622951`	RHSA-2026:42815
Red Hat OpenShift AI 3.4	`rhoai/odh-dashboard-rhel9:1787347991`	RHSA-2026:60520
Red Hat OpenShift AI 3.4	`rhoai/odh-mod-arch-eval-hub-rhel9:1791861214`	RHSA-2026:84734

Frequently Asked Questions

## Summary protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If `Object.prototype` had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information. This could cause attacker-controlled strings to be emitted into generated JavaScript code. ## Impact An attacker who can first trigger a prototype pollution vulnerability may be able to influence generated protobufjs encode or decode functions in a way that can lead to arbitrary JavaScript