Medium, CVSS 4.3npmAmendedPublished
yaml is vulnerable to Stack Overflow via deeply nested YAML collections
CVE-2026-33532 · GHSA-48c2-rrv3-qjmp
- Affected
- npm yaml >= 2.0.0, < 2.8.3; >= 1.0.0, < 1.10.3
- Fixed in
- 1.10.32.8.3· Vendor fix available
- Issue
- Parsing a YAML document with yaml 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…
Recommended action: Upgrade to 2.8.3 or 1.10.3 by release line, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.