CVE-2026-33320 Dasel has unbounded YAML alias expansion in dasel leads to CPU/memory denial of service
An attacker can cause CPU and memory exhaustion in Dasel by supplying malicious YAML input, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33320?
CVE-2026-33320 is a medium-severity denial of service vulnerability in TomWright dasel, published on 24 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Dasel is a command-line tool and library for querying, modifying, and transforming data structures. Starting in version 3.0.0 and prior to version 3.3.1, Dasel's YAML reader allows an attacker who can supply YAML for processing to trigger extreme CPU and memory consumption. The issue is in the library's own `UnmarshalYAML` implementation, which manually resolves alias nodes by recursively following `yaml.Node.Alias` pointers without any expansion budget, bypassing go-yaml v4's built-in alias expansion limit. Version 3.3.2 contains a patch for the issue.
Weakness: CWE-674
Which versions are affected by CVE-2026-33320?
5 open source packages ship an affected version, including github.com/tomwright/dasel/v3, github.com/tomwright/dasel and github.com/tomwright/dasel/v2. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/tomwright/dasel/v3 Go | From 3.0.0 | 3.3.2 |
github.com/tomwright/dasel/v3 Go | From 3.0.0 | 3.3.2 |
github.com/tomwright/dasel/v3 Go | From 3.0.0 | 3.3.2 |
github.com/tomwright/dasel Go | All versions | None |
github.com/tomwright/dasel/v2 Go | All versions | None |
Products include Tomwright Dasel.
How do I fix CVE-2026-33320?
Upgrade github.com/tomwright/dasel/v3 to 3.3.2 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-2026-33320 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33320 exists.
Public exploit code: 3 proofs of concept on GitHub.
Sources
Also known as GHSA-4fcp-jxh7-23x8, GO-2026-4768, UBUNTU-CVE-2026-33320.