CVE-2026-33532

MEDIUM

yaml is vulnerable to Stack Overflow via deeply nested YAML collections

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-33532. PoCs published by danwulff.

AI-analyzed exploit summary The repository contains only a generic Astro Starter Kit README with no exploit code or technical details related to CVE-2026-33532. It appears to be a placeholder or mislabeled repository.

Description

`yaml` is a YAML parser and serialiser for JavaScript. Parsing a YAML document with a version of `yaml` on the 1.x branch prior to 1.10.3 or on the 2.x branch prior to 2.8.3 may throw a RangeError due to a stack overflow. The node resolution/composition phase uses recursive function calls without a depth bound. An attacker who can supply YAML for parsing can trigger a `RangeError: Maximum call stack size exceeded` with a small payload (~2–10 KB). The `RangeError` is not a `YAMLParseError`, so applications that only catch YAML-specific errors will encounter an unexpected exception type. Depending on the host application's exception handling, this can fail requests or terminate the Node.js process. Flow sequences allow deep nesting with minimal bytes (2 bytes per level: one `[` and one `]`). On the default Node.js stack, approximately 1,000–5,000 levels of nesting (2–10 KB input) exhaust the call stack. The exact threshold is environment-dependent (Node.js version, stack size, call stack depth at invocation). Note: the library's `Parser` (CST phase) uses a stack-based iterative approach and is not affected. Only the compose/resolve phase uses actual call-stack recursion. All three public parsing APIs are affected: `YAML.parse()`, `YAML.parseDocument()`, and `YAML.parseAllDocuments()`. Versions 1.10.3 and 2.8.3 contain a patch.

Exploits (1)

nomisec STUB
by danwulff · poc
https://github.com/danwulff/astro_CVE-2026-33532

The repository contains only a generic Astro Starter Kit README with no exploit code or technical details related to CVE-2026-33532. It appears to be a placeholder or mislabeled repository.

Classification
Stub 95%
Attack Type
Other
Complexity
N/a
Reliability
N/a
Target: N/A
No auth needed
devstral-2 · analyzed Apr 08, 2026 Full analysis →

Scores

CVSS v3 4.3
EPSS 0.0003
EPSS Percentile 7.5%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact partial

Details

CWE
CWE-674
Status published
Products (4)
eemeli/yaml 1.0.0 - 1.10.3
eemeli/yaml >= 1.0.0, < 1.10.3
eemeli/yaml >= 2.0.0, < 2.8.3
npm/yaml 2.0.0 - 2.8.3npm
Published Mar 26, 2026
Tracked Since Mar 27, 2026