fix: Catch stack overflow during CST composition

eemeli · eemeli · commit 7abcf45dd63f · 2026-03-21T12:14:26.000+02:00
diff --git a/src/cst/ParseContext.js b/src/cst/ParseContext.js
@@ -196,13 +196,20 @@ export class ParseContext {
         parent: context.parent.type
       }
     const node = createNewNode(type, props)
-    let offset = node.parse(context, valueStart)
+    let offset = start
+    try {
+      offset = node.parse(context, valueStart)
+    } catch (error) {
+      const msg = error instanceof Error ? error.message : String(error)
+      if (!node.error) node.error = new YAMLSyntaxError(node, msg)
+    }
     node.range = new Range(start, offset)
     /* istanbul ignore if */
     if (offset <= start) {
       // This should never happen, but if it does, let's make sure to at least
       // step one character forward to avoid a busy loop.
-      node.error = new Error(`Node#parse consumed no characters`)
+      if (!node.error)
+        node.error = new Error(`Node#parse consumed no characters`)
       node.error.parseEnd = offset
       node.error.source = node
       node.range.end = start + 1
diff --git a/src/resolve/resolveTag.js b/src/resolve/resolveTag.js
@@ -1,7 +1,12 @@
 import { Collection } from '../ast/Collection.js'
 import { Scalar } from '../ast/Scalar.js'
 import { Type, defaultTags } from '../constants.js'
-import { YAMLReferenceError, YAMLWarning } from '../errors.js'
+import {
+  YAMLError,
+  YAMLReferenceError,
+  YAMLSemanticError,
+  YAMLWarning
+} from '../errors.js'
 import { resolveScalar } from './resolveScalar.js'
 import { resolveString } from './resolveString.js'
 
@@ -46,9 +51,13 @@ export function resolveTag(doc, node, tagName) {
       return res
     }
   } catch (error) {
-    /* istanbul ignore if */
-    if (!error.source) error.source = node
-    doc.errors.push(error)
+    if (error instanceof YAMLError) {
+      if (!error.source) error.source = node
+      doc.errors.push(error)
+    } else {
+      const msg = error instanceof Error ? error.message : String(error)
+      doc.errors.push(new YAMLSemanticError(node, msg))
+    }
     return null
   }
 
diff --git a/tests/doc/parse.js b/tests/doc/parse.js
@@ -1,6 +1,7 @@
 import fs from 'fs'
 import path from 'path'
 import YAML from '../../index.js'
+import { YAMLError } from '../../util.js'
 
 describe('tags', () => {
   describe('implicit tags', () => {
@@ -616,6 +617,15 @@ describe('Excessive entity expansion attacks', () => {
   })
 })
 
+test('Excessive recursion', () => {
+  const depth = 5000
+  const src = '['.repeat(depth) + '1' + ']'.repeat(depth)
+  const doc = YAML.parseDocument(src)
+  for (const error of doc.errors) {
+    expect(error).toBeInstanceOf(YAMLError)
+  }
+})
+
 test('Anchor for empty node (6KGN)', () => {
   const src = `a: &anchor\nb: *anchor`
   expect(YAML.parse(src)).toMatchObject({ a: null, b: null })
