CVE-2026-34043 Serialize JavaScript has CPU Exhaustion Denial of Service via crafted array-like objects
Attackers can cause CPU exhaustion and service hang by passing crafted array-like objects to the serialize-javascript library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-34043?
CVE-2026-34043 is a medium-severity denial of service vulnerability in yahoo serialize-javascript, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Serialize JavaScript to a superset of JSON that includes regular expressions and functions. Prior to version 7.0.5, there 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. This issue has been patched in version 7.0.5.
Which versions are affected by CVE-2026-34043?
2 open source packages ship an affected version, including serialize-javascript. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
serialize-javascript npm | From 5.0.0 | 7.0.5 |
serialize-javascript npm | From 5.0.0 | 7.0.5 |
Products include Yahoo Serialize.
How do I fix CVE-2026-34043?
Upgrade serialize-javascript to 7.0.5 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-34043 being exploited?
There is no known exploitation of CVE-2026-34043 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-EZ44935, CLEANSTART-2026-GV24243, CLEANSTART-2026-OD19905, CLSA-2026-1776645371, CLSA-2026-1776645372, DEBIAN-CVE-2026-34043 and 10 more.