CVE-2026-107298 msgpack5: Deeply nested input can exhaust the decoder stack
Attackers can cause denial of service in applications using msgpack5 by submitting deeply nested MessagePack data that exhausts the call stack.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-107298?
CVE-2026-107298 is a medium-severity denial of service vulnerability in mcollina msgpack5, published on 8 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the array and map decoding paths have no nesting-depth limit, allowing an attacker who can provide MessagePack input to submit deeply nested containers that exhaust the JavaScript call stack and interrupt a process, worker, or request handler. This issue is fixed in version 6.1.0.
Weakness: CWE-674
Which versions are affected by CVE-2026-107298?
2 open source packages ship an affected version, including msgpack5.
| Package | Affected | Fixed in |
|---|---|---|
msgpack5 npm | All versions | 6.1.0 |
msgpack5 npm | All versions | 6.1.0 |
How do I fix CVE-2026-107298?
Upgrade msgpack5 to 6.1.0 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-2026-107298 being exploited?
There is no known exploitation of CVE-2026-107298 in the wild and no public exploit code.
Sources
Also known as AZL-106860, GHSA-24ch-f2g6-9hhh.