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EUVD-2026-277500

fkie_cve-2026-33320

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.

GHSA-4fcp-jxh7-23x8 — Dasel has unbounded YAML alias expansion in dasel leads to CPU/memory denial of service

Affected: Go: github.com/tomwright/dasel/v3

### Summary

`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.

The issue issue is on `v3.3.1` (`fba653c7f248aff10f2b89fca93929b64707dfc8`) and on the current default branch at commit `0dd6132e0c58edbd9b1a5f7ffd00dfab1e6085ad`. It is also verified the same code path is present in `v3.0.0` (`648f83baf070d9e00db8ff312febef857ec090a3`). A 342-byte payload did not complete within 5 seconds on the test system and exhibited unbounded resource growth.

### Details

In `v3.3.1` (`fba653c7f248aff10f2b89fca93929b64707dfc8`), the reachable call path is:

- The YAML reader is registered in [`parsing/yaml/yaml.go`](https://github.com/TomWright/dasel/blob/fba653c7f248aff10f2b89fca93929b64707dfc8/parsing/yaml/yaml.go) and exposed via `parsing.Format("yaml").NewReader()` - `(*yamlReader).Read` in [`parsing/yaml/yaml_reader.go#L23-L48`](https://github.com/TomWright/dasel/blob/fba653c7f248aff10f2b89fca93929b64707dfc8/parsing/yaml/yaml_reader.go#L23-L48) uses `yaml.NewDecoder` to decode the input. Because `yamlValue` implements `UnmarshalYAML(*yaml.Node)`, the decoder passes the raw `*yaml.Node` tree to that custom unmarshaler - `(*yamlValue).UnmarshalYAML` in [`parsing/yaml/yaml_reader.…

UBUNTU-CVE-2026-33320

Affected: Ubuntu:Pro:24.04:LTS: dasel, Ubuntu:25.10: dasel, Ubuntu:26.04:LTS: dasel