How severe is CVE-2026-45740?

CVE-2026-45740 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-45740?

CVE-2026-45740 affects the following packages: protobufjs (npm), protobufjs (npm). Ecosystems affected: npm.

How do I fix CVE-2026-45740?

Update protobufjs to 7.5.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45740 is resolved across your whole dependency graph.

How do I detect CVE-2026-45740 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-2026-45740 if there is no patch (or I can't update yet)?

Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Is CVE-2026-45740 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-45740 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-2026-45740?

CVE-2026-45740 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 37th 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-2026-45740?

CVE-2026-45740 is classified as CWE-674 (CWE-674). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-45740 published, and has it been updated?

CVE-2026-45740 was published on May 13, 2026 and was last updated on August 12, 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

MEDIUM severity

CVE-2026-45740 — protobufjs

MEDIUM

CVE-2026-45740 is a medium-severity (CVSS 5.3) CWE-674 vulnerability in protobufjs. A fix is available for protobufjs — see the affected versions and patch details below.

protobufjs: Denial of Service via unbounded recursive JSON descriptor expansion

Also known asGHSA-jggg-4jg4-v7c6

Published

May 13, 2026

Updated

Aug 12, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Sep 26, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
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-2026-45740.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs37th percentile — riskier than 37% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2026-45740 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 380,526 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.

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

protobufjsnpm

98.4Mdownloads / week

Description

Summary

protobufjs could recurse without a depth limit while expanding nested JSON descriptors through Root.fromJSON() and Namespace.addJSON().

A crafted JSON descriptor with deeply nested namespace definitions could cause the JavaScript call stack to be exhausted during descriptor loading.

Impact

An attacker who can provide JSON descriptors loaded by an application may be able to crash the process or otherwise cause schema loading to fail with a stack overflow.

This affects applications that load JSON descriptors from untrusted sources with affected versions.

Preconditions

The application must load JSON descriptor data influenced by an attacker.
The crafted descriptor must contain deeply nested nested namespace objects.
The affected Root.fromJSON() / Namespace.addJSON() descriptor expansion path must process the crafted input.

Workarounds

Avoid loading untrusted protobuf JSON descriptors with affected versions. If immediate upgrade is not possible, reject excessively nested descriptor structures at an outer validation boundary where feasible, or isolate descriptor loading in a process that can be safely restarted.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`protobufjs`	all versions	7.5.8`npm install protobufjs@7.5.8`
📦npm	`protobufjs`	≥ 8.0.0&&< 8.2.0	8.2.0`npm install protobufjs@8.2.0`

Affected Products

1 product · 2 configurations

Application

protobufjsprotobufjs_project

≥ 8.0.0 && < 8.2.0

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 7.5.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45740 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

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 is an Important denial of service flaw in protobufjs, which could allow a remote attacker to exhaust the JavaScript call stack by providing a specially crafted JSON descriptor with deeply nested namespace definitions. This vulnerability impacts Red Hat products that utilize protobufjs for processing protobuf…

Workaround published by Red Hat

To mitigate this issue, avoid loading untrusted protobuf JSON descriptors in applications utilizing protobufjs. If untrusted descriptors must be processed, implement validation at an outer boundary to reject excessively nested structures. Alternatively, isolate the descriptor loading process in an environment that can be safely restarted in case of a denial of service.

Source: Red Hat security advisory for CVE-2026-45740 (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 Enterprise Linux 10	`rh-podman-desktop-0:1.1.2-1.el10_2`	RHSA-2026:57590
Red Hat Ansible Automation Platform 2.2	`ansible-automation-platform/automation-portal:1784622951`	RHSA-2026:42815
Red Hat Ansible Automation Platform 2.2	`ansible-automation-platform/bootc-automation-portal-rhel9:1786006573`	RHSA-2026:51162
Red Hat Developer Hub 1.10	`rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend:1785332487`	RHSA-2026:48126
Red Hat Developer Hub 1.10	`rhdh/rhdh-hub-rhel9:1785411652`	RHSA-2026:49642
Red Hat Developer Hub 1.9	`rhdh/rhdh-hub-rhel9:1784210921`	RHSA-2026:41929
Red Hat OpenShift AI 3.4	`rhoai/odh-dashboard-rhel9:1787347991`	RHSA-2026:60520

Frequently Asked Questions

## Summary protobufjs could recurse without a depth limit while expanding nested JSON descriptors through `Root.fromJSON()` and `Namespace.addJSON()`. A crafted JSON descriptor with deeply nested namespace definitions could cause the JavaScript call stack to be exhausted during descriptor loading. ## Impact An attacker who can provide JSON descriptors loaded by an application may be able to crash the process or otherwise cause schema loading to fail with a stack overflow. This affects applications that load JSON descriptors from untrusted sources with affected versions. ## Preconditions