CVE-2026-34043 is a medium-severity (CVSS 5.9) Uncontrolled Resource Consumption vulnerability in serialize-javascript. A fix is available for serialize-javascript — see the affected versions and patch details below.
Serialize JavaScript has CPU Exhaustion Denial of Service via crafted array-like objects
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 CVE-2026-34043.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-34043 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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.
serialize-javascriptnpmDescription
Impact
What kind of vulnerability is it?
It is a Denial of Service (DoS) vulnerability caused by CPU exhaustion. When serializing a specially crafted "array-like" object (an object that inherits from Array.prototype but has a very large length property), the process enters an intensive loop that consumes 100% CPU and hangs indefinitely.
Who is impacted?
Applications that use serialize-javascript to serialize untrusted or user-controlled objects are at risk. While direct exploitation is difficult, it becomes a high-priority threat if the application is also vulnerable to Prototype Pollution or handles untrusted data via YAML Deserialization, as these could be used to inject the malicious object.
Patches
Has the problem been patched?
Yes, the issue has been patched by replacing instanceof Array checks with Array.isArray() and using Object.keys() for sparse array detection.
What versions should users upgrade to?
Users should upgrade to v7.0.5 or later.
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
There is no direct code-level workaround within the library itself. However, users can mitigate the risk by:
- Validating and sanitizing all input before passing it to the
serialize()function. - Ensuring the environment is protected against Prototype Pollution.
- Upgrading to
v7.0.5as soon as possible.
Acknowledgements
Serialize JavaScript thanks Tomer Aberbach (@TomerAberbach) for discovering and privately disclosing this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | serialize-javascript | ≥ 5.0.0&&< 7.0.5 | 7.0.5npm install serialize-javascript@7.0.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for serialize-javascript, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update serialize-javascript to 7.0.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34043 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34043 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34043. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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 Hat products in their default configurations do not accept input from unauthenticated users.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | dotnet8.0-0:8.0.127-1.el10_2 | RHSA-2026:21286 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | dotnet8.0-0:8.0.127-1.el10_0 | RHSA-2026:24332 |
| Red Hat Enterprise Linux 8 | dotnet8.0-0:8.0.127-1.el8_10 | RHSA-2026:21291 |
| Red Hat Enterprise Linux 9 | dotnet8.0-0:8.0.127-1.el9_8 | RHSA-2026:21293 |
| Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions | dotnet8.0-0:8.0.127-1.el9_4 | RHSA-2026:24334 |
| Red Hat Enterprise Linux 9.6 Extended Update Support | dotnet8.0-0:8.0.127-1.el9_6 | RHSA-2026:24335 |
| Red Hat OpenShift Container Platform 4.16 | openshift4/ose-networking-console-plugin-rhel9:1782211435 | RHSA-2026:29082 |
| Red Hat OpenShift Container Platform 4.17 | openshift4/ose-networking-console-plugin-rhel9:1782185607 | RHSA-2026:34099 |
Frequently Asked Questions
Is CVE-2026-34043 in your dependencies?
O3 Security finds CVE-2026-34043 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.