Answer in brief
CVE-2021-4235 records a Medium severity (CVSS 5.5) vulnerability in YAML Go package vulnerable to denial of service. The current sources do not mark it as known exploited. The current feed maps github.com/go-yaml/yaml (go), gopkg.in/yaml.v2 (go). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps github.com/go-yaml/yaml (go), gopkg.in/yaml.v2 (go). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/go-yaml/yamlgo | >=0 | Not reported |
| gopkg.in/yaml.v2go | >=0 <2.2.3 | 2.2.3 |
Published upstream
Dec 28, 2022
Evidence: source:osv:source_dates:source-dates:recordSource modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:recordFirst seen by HOL
Aug 7, 2026
Due to unbounded alias chasing, a maliciously crafted YAML file can cause the system to consume significant system resources. If parsing user input, this may be used as a denial of service vector.
Quoted source text, attributed separately from HOL analysis.