# CVE-2026-33532: yaml stack overflow via deeply nested collections

Source: https://junglewise.ai/threats/cve-2026-33532-yaml-stack-overflow-via-deeply-nested-collections  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-25. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-33532 · Severity: low · CVSS 3.1 · Published 2026-03-25

The yaml JavaScript library is vulnerable to a denial-of-service condition when parsing YAML documents with deeply nested collections. An attacker can supply a small malicious YAML payload (as small as 2–10 KB) that triggers a stack overflow, causing the application to throw an unhandled exception and potentially crash. Applications that only expect YAML-specific errors may fail to catch this exception type, leading to service disruption.

## Quick answers

**Is CVE-2026-33532 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-33532 being exploited in the wild.

**How severe is CVE-2026-33532?** Low severity, with a CVSS score of 3.1, published 25 March 2026.

**Which products and versions are affected?** Yaml SEMVER:introduced=2.0.0,fixed=2.8.3.

**Is there a fix for CVE-2026-33532?** Yes. Yaml: upgrade to 2.8.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-33532 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-33532?** Check whether you run Yaml at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Yaml: upgrade to 2.8.3 or later

## Technical details

The vulnerability exists in the node composition/resolution phase of yaml's parser, which uses recursive function calls without depth bounds. While the CST (Concrete Syntax Tree) phase uses iterative stack-based processing and is unaffected, the compose/resolve phase recursively processes nested nodes. Flow sequences are particularly efficient for exploitation, requiring only 2 bytes per nesting level (one `[` and one `]`). On typical Node.js environments with default stack sizes, approximately 1,000–5,000 levels of nesting (2–10 KB input) exhaust the call stack and trigger a RangeError. The exception is not a YAMLParseError, so applications that selectively catch only YAML-specific errors will encounter an unexpected exception type. All three public parsing APIs are affected: `YAML.parse()`, `YAML.parseDocument()`, and `YAML.parseAllDocuments()`. Patches addressing this issue were released in versions 1.10.3 and 2.8.3, which catch the stack overflow and convert it to a YAMLParseError with code `RESOURCE_EXHAUSTION`.

## Affected products

- eemeli yaml 1.0.0 through 1.10.2, 2.0.0 through 2.8.2

## Identifiers

- CVE-2026-33532
- GHSA-48c2-rrv3-qjmp

## Timeline

- 2026-03-25: disclosed: Security advisory published on GitHub
- 2026-03-21: patched: Fix committed (v1.10.3 and v2.8.3 released on March 21, 2026)

## References

- [https://github.com/eemeli/yaml/security/advisories/GHSA-48c2-rrv3-qjmp](https://github.com/eemeli/yaml/security/advisories/GHSA-48c2-rrv3-qjmp)
- [https://github.com/eemeli/yaml/commit/1e84ebbea7ec35011a4c61bbb820a529ee4f359b](https://github.com/eemeli/yaml/commit/1e84ebbea7ec35011a4c61bbb820a529ee4f359b)
- [https://github.com/eemeli/yaml](https://github.com/eemeli/yaml)
- [https://github.com/eemeli/yaml/releases/tag/v1.10.3](https://github.com/eemeli/yaml/releases/tag/v1.10.3)
- [https://github.com/eemeli/yaml/releases/tag/v2.8.3](https://github.com/eemeli/yaml/releases/tag/v2.8.3)

## Related threats

- [eemeli yaml uncaught exception in error printer](https://junglewise.ai/threats/cve-2023-2251-eemeli-yaml-uncaught-exception-in-error-printer)